1.nounA misunderstanding of the etymology of a word appealing to the unlearned mind; an etymology that incorrectly explains the origin of a word based on a judgement out of knowledge or passions of a common speaker of the language instead of expertise in its past.
"Many folk etymologies involve backronyms."
2.nounA modification of a word or its spelling resulting from a misunderstanding of its etymology, as with island, belfry, and hangnail.