unscientific etymology; popular but incorrect notion of the origin and derivation of a word: folk etymology may bring about change, as in the case of “cole slaw” becoming “cold slaw”
See folk etymology in American Heritage Dictionary 4
noun
Change in the form of a word or phrase resulting from a mistaken assumption about its composition or meaning, as in shamefaced for earlier shamfast, “bound by shame,” or cutlet from French côtelette, “little rib.”