flab

The word 'flab' is a relatively modern English coinage, first appearing in the late 19th century. It originated as a humorous or colloquial back-formation from the adjective 'flabby', which itself dates to the late 17th century. The core of 'flabby' is thought to be an alteration of 'flappy', derived from the verb 'flap', a Middle English word of imitative origin, evoking the sound and motion of something loose and soft striking or waving. Thus, 'flab' carries the inherent sense of soft, loose flesh that can shake or move independently, a meaning directly inherited from its expressive, onomatopoeic roots.

The word 'flab' is a simplex word, likely formed by alteration and shortening of an existing word. It is considered a back-formation from 'flabby', with the '-y' adjectival suffix removed to create a noun. Its ultimate origin is imitative or expressive, possibly related to words like 'flap' or 'flabby' which suggest a loose, waving motion.