unique (adj.)youdaoicibaDictYouDict[unique 词源字典]
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.[unique etymology, unique origin, 英语词源]
unity (n.)youdaoicibaDictYouDict
c. 1300, "state or property of being one," from Anglo-French unite, Old French unite "uniqueness, oneness" (c. 1200), from Latin unitatem (nominative unitas) "oneness, sameness, agreement," from unus "one" (see one).