Some people use the term folk etymology to describe a fanciful story behind a word's origin. But etymologists use this term in a very specific, and different, way. Folk etymology is when an unfamiliar word is altered through common use to resemble a more familiar word. Hence, through the process of folk etymology cater corner becomes kitty corner . Functional Shift Words often shift their grammatical function over time.
Nouns become verbs, verbs become nouns, nouns become adjectives, etc.
Run was originally a verb, dating back to about the year 800, but in the 15th century people started using it as a noun, as in to go for a run . Some grammarians decry functional shifts as improper English, but it is a natural process. There are four distinct sub-classes of word formation through abbreviation . These are initialisms, acronyms, clipped forms, and back formations. In initialisms and acronyms , the initial portions of the words or syllables of a phrase are used to from a word.