2、un-, 一，词源同unit,-que, 形容词后缀。
2、unique:  Unique comes via French unique from Latin ūnicus ‘only, sole’. This was derived from ūnus ‘one’, a distant relative of English one. It originally meant simply ‘single, sole’ in English, and the extended sense ‘unequalled, unparalleled’, which has often drawn the hostile criticism of purists (particularly when accompanied by qualifiers such as very or completely), did not emerge until the late 18th century, under French influence.=> one, union
4、c. 1600,"single, solitary,"from Middle French unique (16c.), from Latin unicus"only, single, sole, alone of its kind,"from unus"one"(see one). Meaning"forming the only one of its kind"is attested from 1610s; erroneous sense of"remarkable, uncommon"is attested from mid-19c. Related: Uniquely; uniqueness.