What the Fallacy?!
Etymological Fallacy
The Fallacy
Arguing that the present-day meaning of a word or phrase must be exactly the same as its historical or original meaning.
Why it's wrong
Languages evolve, and words frequently shift in meaning over time. Asserting that a word must be used according to its ancient roots ignores its current, accepted usage and can lead to misleading or confused arguments.
Example
The word 'decimate' historically means to destroy exactly one-tenth. Therefore, you can't say the hurricane decimated the town unless exactly ten percent of it was ruined.