superfluous

the word 'superfluous' originates from latin 'superfluus', meaning "overflowing, running over". this is a compound of 'super-' (over, above) and 'fluere' (to flow). the literal image is of a liquid flowing over the rim of a container. this concrete meaning evolved through latin and middle english to acquire the abstract sense of an excess that goes beyond what is necessary or sufficient. the logical progression from a physical overflow to a metaphorical excess illustrates how the word's core meaning of "overflowing" was retained while its application broadened to describe any kind of unnecessary surplus.