system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is a refrigerator referred to as just a fridge, why does the shortened version have a "d" in it, and what is the purpose of the "re" prefix of it?
gpt
The word "refrigerate" was coined in the 15th century from the Latin which means "make cool again"; the sense of "again" was important, because originally it had the sense of taking away a sick person's fever -- returning them to their normal cool state. It was then simply extended to mean "make something cool" in a general sense, and the "re-" prefix lost all meaning. The word "refrigerator" to mean "a device that keeps something cool" is surprisingly old: it dates from the 17th century. There was also "refrigeratory" to mean "room for keeping things cool", very useful for beer brewers. In the 19th century, refrigeratories had been replaced by cabinets called refrigerators, and by the 20th century there were electrically powered refrigerators.

The word "refrigerator" was shortened to "fridge" by the 1920s, either in the same way that "telephone" was shortened to "phone", or influenced by a popular manufacturer of the devices, Frigidaire -- nobody's sure which it is.

The "d" is added by analogy with words like "bridge". How else would you spell it? If you spell it "frig", then it would have a hard "g"; if you spell it "frige", then it would have a long "i". You need the "e" to keep the "g" soft, but then to keep the "i" short you need to write at least two consonants. The rules of English orthography are such that you need to write "dg" for a soft "g" sound after a short vowel.