I apologize for such a simple and stupid question but the word is completely skipping my mind and my google fu seems to be failing me for this one.
An example would be something along the lines of shit to poop or fuck to fudge.
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Perhaps you are thinking of the word euphemism, which has senses “The use of a word or phrase to replace another with one that is considered less offensive, blunt or vulgar than the word or phrase it replaces” and “A word or phrase that is used to replace another in this way.”
Some words that are related to the topic (but probably don't quite fit the context of the question) are bowdlerize (“To remove or alter those parts of a text considered offensive, vulgar, or otherwise unseemly”), gentrify (“to renovate something, especially housing, to make it more appealing to the middle classes”), and expurgate (“To edit out rude, incorrect, offensive, useless, or otherwise undesirable information from a book, CD or other publication; to cleanse; to purge”).