user6307: I've been doing some tag clean-up (sorry for all the bumps) and came across a few that, in my opinion, should be synonyms. I don't have the privilege to make these changes, but perhaps someone who does, and thinks they should be synonyms, can. For many of these tags, there are few users who can suggest/vote on them so moderator intervention may be required.
Proposed:

experimental-design ← experiment, experimental - These tags seem redundant.
materials ← lab-reagents - I recently create the materials tag as a complement to the methods tag and to cover questions that aren't about reagents. I think having the more derived tag lab-reagents is unnecessary given the large overlap and infrequent use.
methods ← lab-techniques - For the same reason as the lab-reagents tag.

Completed:

lymphatic ← lymph - I don't particularly like either of these tags. Perhaps we can make a new tag called lymphatic-system or lymphology (analgous to the current cardiology and oncology tags) and make both of the existing tags synonyms?
oncology ← cancer, tumor, tumour - These tags all seem redundant.
species-identification ← identification - I haven't seen the latter tag used in any question not requesting species identification, nor can I think of a use case outside of species identification.
biochemistry ← chemistry - These two are often used in conjunction. I also cannot think of a question that would be on-topic here which would require the chemistry tag but not the biochemistry tag.
literature ← reference-request - Related to this topic. reference-request seems unnecessary since, to me, using the literature tag in an implicit request for a reference. The literature tag wiki can be edited to specify that it can be used for to request references.


user3340: 
Merged oncology and tumor with cancer and also created oncology as a synonym of cancer. I chose to keep cancer as the primary tag because it is more common and better understood than oncology. 
Created a lymphatic-system and merged lymph and
lymphatic with it. Also, synonymised lymph with
lymphatic-system.
Merged and synonymized identification with species-identification. All the questions under identification but without species-identification were basically species identification questions. One question was different and was about terminology, so tagged appropriately. Since 84 questions were tagged with identification it seemed apt to make it a synonym of species-identification so that in future, the former does not accumulate. 
Merged chemistry with biochemistry. I agree that chemistry has no meaning in this site if it is not biochemistry.
Merged and synonymized reference-request with literature. book-recommendation is still separate. We should have a consensus on whether it should be merged with literature.


I am not sure about other suggestions. Your suggestions are logical but the existing tag names seem to be more popular. If others agree for the change then we can rename those tags. At present it seems unnecessary to me. 

6307: <p>I've been doing some tag clean-up (sorry for all the bumps) and came across a few that, in my opinion, should be synonyms. I don't have the privilege to make these changes, but perhaps someone who does, and thinks they should be synonyms, can. For many of these tags, there are few users who can suggest/vote on them so moderator intervention may be required.</p>

<p><strong>Proposed:</strong></p>

<ul>
<li><a href="https://biology.stackexchange.com/questions/tagged/experimental-design" class="post-tag" title="show questions tagged &#39;experimental-design&#39;" rel="tag">experimental-design</a> ← <a href="https://biology.stackexchange.com/questions/tagged/experiment" class="post-tag" title="show questions tagged &#39;experiment&#39;" rel="tag">experiment</a>, <a href="https://biology.stackexchange.com/questions/tagged/experimental" class="post-tag" title="show questions tagged &#39;experimental&#39;" rel="tag">experimental</a> - These tags seem redundant.</li>
<li><a href="https://biology.stackexchange.com/questions/tagged/materials" class="post-tag" title="show questions tagged &#39;materials&#39;" rel="tag">materials</a> ← <a href="https://biology.stackexchange.com/questions/tagged/lab-reagents" class="post-tag" title="show questions tagged &#39;lab-reagents&#39;" rel="tag">lab-reagents</a> - I recently create the <a href="https://biology.stackexchange.com/questions/tagged/materials" class="post-tag" title="show questions tagged &#39;materials&#39;" rel="tag">materials</a> tag as a complement to the <a href="https://biology.stackexchange.com/questions/tagged/methods" class="post-tag" title="show questions tagged &#39;methods&#39;" rel="tag">methods</a> tag and to cover questions that aren't about reagents. I think having the more derived tag <a href="https://biology.stackexchange.com/questions/tagged/lab-reagents" class="post-tag" title="show questions tagged &#39;lab-reagents&#39;" rel="tag">lab-reagents</a> is unnecessary given the large overlap and infrequent use.</li>
<li><a href="https://biology.stackexchange.com/questions/tagged/methods" class="post-tag" title="show questions tagged &#39;methods&#39;" rel="tag">methods</a> ← <a href="https://biology.stackexchange.com/questions/tagged/lab-techniques" class="post-tag" title="show questions tagged &#39;lab-techniques&#39;" rel="tag">lab-techniques</a> - For the same reason as the <a href="https://biology.stackexchange.com/questions/tagged/lab-reagents" class="post-tag" title="show questions tagged &#39;lab-reagents&#39;" rel="tag">lab-reagents</a> tag.</li>
</ul>

<p><strong>Completed:</strong></p>

<ul>
<li><a href="https://biology.stackexchange.com/questions/tagged/lymphatic" class="post-tag" title="show questions tagged &#39;lymphatic&#39;" rel="tag">lymphatic</a> ← <a href="https://biology.stackexchange.com/questions/tagged/lymph" class="post-tag" title="show questions tagged &#39;lymph&#39;" rel="tag">lymph</a> - I don't particularly like either of these tags. Perhaps we can make a new tag called <a href="https://biology.stackexchange.com/questions/tagged/lymphatic-system" class="post-tag" title="show questions tagged &#39;lymphatic-system&#39;" rel="tag">lymphatic-system</a> or <a href="https://biology.stackexchange.com/questions/tagged/lymphology" class="post-tag" title="show questions tagged &#39;lymphology&#39;" rel="tag">lymphology</a> (analgous to the current <a href="https://biology.stackexchange.com/questions/tagged/cardiology" class="post-tag" title="show questions tagged &#39;cardiology&#39;" rel="tag">cardiology</a> and <a href="https://biology.stackexchange.com/questions/tagged/oncology" class="post-tag" title="show questions tagged &#39;oncology&#39;" rel="tag">oncology</a> tags) and make both of the existing tags synonyms?</li>
<li><a href="https://biology.stackexchange.com/questions/tagged/oncology" class="post-tag" title="show questions tagged &#39;oncology&#39;" rel="tag">oncology</a> ← <a href="https://biology.stackexchange.com/questions/tagged/cancer" class="post-tag" title="show questions tagged &#39;cancer&#39;" rel="tag">cancer</a>, <a href="https://biology.stackexchange.com/questions/tagged/tumor" class="post-tag" title="show questions tagged &#39;tumor&#39;" rel="tag">tumor</a>, <a href="https://biology.stackexchange.com/questions/tagged/tumour" class="post-tag" title="show questions tagged &#39;tumour&#39;" rel="tag">tumour</a> - These tags all seem redundant.</li>
<li><a href="https://biology.stackexchange.com/questions/tagged/species-identification" class="post-tag" title="show questions tagged &#39;species-identification&#39;" rel="tag">species-identification</a> ← <a href="https://biology.stackexchange.com/questions/tagged/identification" class="post-tag" title="show questions tagged &#39;identification&#39;" rel="tag">identification</a> - I haven't seen the latter tag used in any question not requesting species identification, nor can I think of a use case outside of species identification.</li>
<li><a href="https://biology.stackexchange.com/questions/tagged/biochemistry" class="post-tag" title="show questions tagged &#39;biochemistry&#39;" rel="tag">biochemistry</a> ← <a href="https://biology.stackexchange.com/questions/tagged/chemistry" class="post-tag" title="show questions tagged &#39;chemistry&#39;" rel="tag">chemistry</a> - These two are often used in conjunction. I also cannot think of a question that would be on-topic here which would require the <a href="https://biology.stackexchange.com/questions/tagged/chemistry" class="post-tag" title="show questions tagged &#39;chemistry&#39;" rel="tag">chemistry</a> tag but not the <a href="https://biology.stackexchange.com/questions/tagged/biochemistry" class="post-tag" title="show questions tagged &#39;biochemistry&#39;" rel="tag">biochemistry</a> tag.</li>
<li><a href="https://biology.stackexchange.com/questions/tagged/literature" class="post-tag" title="show questions tagged &#39;literature&#39;" rel="tag">literature</a> ← <a href="https://biology.stackexchange.com/questions/tagged/reference-request" class="post-tag" title="show questions tagged &#39;reference-request&#39;" rel="tag">reference-request</a> - Related to <a href="https://biology.meta.stackexchange.com/questions/3570/cleaning-up-the-literature-tags">this topic</a>. <a href="https://biology.stackexchange.com/questions/tagged/reference-request" class="post-tag" title="show questions tagged &#39;reference-request&#39;" rel="tag">reference-request</a> seems unnecessary since, to me, using the <a href="https://biology.stackexchange.com/questions/tagged/literature" class="post-tag" title="show questions tagged &#39;literature&#39;" rel="tag">literature</a> tag in an implicit request for a reference. The <a href="https://biology.stackexchange.com/questions/tagged/literature" class="post-tag" title="show questions tagged &#39;literature&#39;" rel="tag">literature</a> tag wiki can be edited to specify that it can be used for to request references.</li>
</ul>
 3340: <ul>
<li>Merged <a href="https://biology.stackexchange.com/questions/tagged/oncology" class="post-tag" title="show questions tagged &#39;oncology&#39;" rel="tag">oncology</a> and <a href="https://biology.stackexchange.com/questions/tagged/tumor" class="post-tag" title="show questions tagged &#39;tumor&#39;" rel="tag">tumor</a> with <a href="https://biology.stackexchange.com/questions/tagged/cancer" class="post-tag" title="show questions tagged &#39;cancer&#39;" rel="tag">cancer</a> and also created <a href="https://biology.stackexchange.com/questions/tagged/oncology" class="post-tag" title="show questions tagged &#39;oncology&#39;" rel="tag">oncology</a> as a synonym of <a href="https://biology.stackexchange.com/questions/tagged/cancer" class="post-tag" title="show questions tagged &#39;cancer&#39;" rel="tag">cancer</a>. I chose to keep <a href="https://biology.stackexchange.com/questions/tagged/cancer" class="post-tag" title="show questions tagged &#39;cancer&#39;" rel="tag">cancer</a> as the primary tag because it is more common and better understood than oncology. </li>
<li>Created a <a href="https://biology.stackexchange.com/questions/tagged/lymphatic-system" class="post-tag" title="show questions tagged &#39;lymphatic-system&#39;" rel="tag">lymphatic-system</a> and merged <a href="https://biology.stackexchange.com/questions/tagged/lymph" class="post-tag" title="show questions tagged &#39;lymph&#39;" rel="tag">lymph</a> and
<a href="https://biology.stackexchange.com/questions/tagged/lymphatic" class="post-tag" title="show questions tagged &#39;lymphatic&#39;" rel="tag">lymphatic</a> with it. Also, synonymised <a href="https://biology.stackexchange.com/questions/tagged/lymph" class="post-tag" title="show questions tagged &#39;lymph&#39;" rel="tag">lymph</a> with
<a href="https://biology.stackexchange.com/questions/tagged/lymphatic-system" class="post-tag" title="show questions tagged &#39;lymphatic-system&#39;" rel="tag">lymphatic-system</a>.</li>
<li>Merged and synonymized <a href="https://biology.stackexchange.com/questions/tagged/identification" class="post-tag" title="show questions tagged &#39;identification&#39;" rel="tag">identification</a> with <a href="https://biology.stackexchange.com/questions/tagged/species-identification" class="post-tag" title="show questions tagged &#39;species-identification&#39;" rel="tag">species-identification</a>. All the questions under <a href="https://biology.stackexchange.com/questions/tagged/identification" class="post-tag" title="show questions tagged &#39;identification&#39;" rel="tag">identification</a> but without <a href="https://biology.stackexchange.com/questions/tagged/species-identification" class="post-tag" title="show questions tagged &#39;species-identification&#39;" rel="tag">species-identification</a> were basically species identification questions. One question was different and was about terminology, so tagged appropriately. Since 84 questions were tagged with <a href="https://biology.stackexchange.com/questions/tagged/identification" class="post-tag" title="show questions tagged &#39;identification&#39;" rel="tag">identification</a> it seemed apt to make it a synonym of <a href="https://biology.stackexchange.com/questions/tagged/species-identification" class="post-tag" title="show questions tagged &#39;species-identification&#39;" rel="tag">species-identification</a> so that in future, the former does not accumulate. </li>
<li>Merged <a href="https://biology.stackexchange.com/questions/tagged/chemistry" class="post-tag" title="show questions tagged &#39;chemistry&#39;" rel="tag">chemistry</a> with <a href="https://biology.stackexchange.com/questions/tagged/biochemistry" class="post-tag" title="show questions tagged &#39;biochemistry&#39;" rel="tag">biochemistry</a>. I agree that <a href="https://biology.stackexchange.com/questions/tagged/chemistry" class="post-tag" title="show questions tagged &#39;chemistry&#39;" rel="tag">chemistry</a> has no meaning in this site if it is not <a href="https://biology.stackexchange.com/questions/tagged/biochemistry" class="post-tag" title="show questions tagged &#39;biochemistry&#39;" rel="tag">biochemistry</a>.</li>
<li>Merged and synonymized <a href="https://biology.stackexchange.com/questions/tagged/reference-request" class="post-tag" title="show questions tagged &#39;reference-request&#39;" rel="tag">reference-request</a> with <a href="https://biology.stackexchange.com/questions/tagged/literature" class="post-tag" title="show questions tagged &#39;literature&#39;" rel="tag">literature</a>. <a href="https://biology.stackexchange.com/questions/tagged/book-recommendation" class="post-tag" title="show questions tagged &#39;book-recommendation&#39;" rel="tag">book-recommendation</a> is still separate. We should have a consensus on whether it should be merged with <a href="https://biology.stackexchange.com/questions/tagged/literature" class="post-tag" title="show questions tagged &#39;literature&#39;" rel="tag">literature</a>.</li>
</ul>

<hr>

<p>I am not sure about other suggestions. Your suggestions are logical but the existing tag names seem to be more popular. If others agree for the change then we can rename those tags. At present it seems unnecessary to me. </p>
