The word 'unequal' is formed by the straightforward combination of the native English negative prefix 'un-' and the adjective 'equal'. 'Equal' itself descends from the Latin 'aequalis', meaning "uniform, identical, just," which derives from 'aequus' ("level, even"). The core concept of 'aequus' relates to flatness and balance, a physical metaphor that evolved into abstract notions of fairness and equivalence. Therefore, 'unequal' literally means "not level or even," a meaning that extends directly from the physical to describe both mathematical disparity and social injustice.

Structure: un (not) + equal (same, fair) - un: A prefix of Germanic origin (Old English 'un-'), meaning "not." It functions as a negative particle. - equal: From Latin 'aequus' meaning "level, even, just." In this word, it functions as the adjectival base meaning "the same in quantity, size, degree, or value."