Some good counter-examples to show up the etymological fallacy:
prodigy:
"Back in the 15th century the word's meaning was more strongly influenced by that of its Latin ancestor, "prodigium," meaning "omen" or "monster.""
oaf:
"A long time ago in England, it was believed that goblins sometimes secretly exchanged their babies for human babies. This was used as an explanation when parents found themselves with a particularly ugly or deformed child: these parents wanted to believe that their real baby had been stolen by goblins, and the other left in its place. The label for such a child was "auf," or "alfe" (meaning "goblin's child"), terms that were later altered to form our present-day "oaf." Although the linguistic history is not entirely clear, "auf" and "alfe" are likely from the Middle English "alven" and "elven," meaning "elf" or "fairy." Today the word "oaf" is no longer associated with unattractive babies and is instead applied to anyone who appears especially unintelligent or graceless."
bigot:
"Bigots may have more in common with God than one might think. Legend has it that Rollo, the first duke of Normandy, refused to kiss the foot of the French king Charles III, uttering the phrase bi got, his borrowing of the assumed Old English equivalent of our expression by God. Although this story is almost surely apocryphal, it is true that bigot was used by the French as a term of abuse for the Normans, but not in a religious sense. Later, however, the word, or very possibly a homonym, was used abusively in French for the Beguines, members of a Roman Catholic lay sisterhood. From the 15th century on Old French bigot meant "an excessively devoted or hypocritical person." Bigot is first recorded in English in 1598 with the sense "a superstitious hypocrite.""
Addendum: There's also "lunacy" and "hysteria"