import re


def keep_only_letters(word_list):
	"""
	Remove all non letter charachter from each element of a list

	:type word_list: list(str)
	:param word_list: The list of word to remove all non-letters from
	"""
	new_word_list = list()
	for word in word_list:
		word = re.sub(r'[^A-Za-z-]+','',word)
		new_word_list.append(word)

	return new_word_list