also depersonalisation, "loss of personality, a treating as though not having a personal identity," 1893, noun of action from depersonalize "regard as not individually personal;" see de- "do the opposite of" +  personalize. Related: Depersonalized; depersonalizing.

also mid-life, 1837, from mid (adj.) + life. Middle-life is from early 14c. Midlife crisis "transition of identity and self-confidence that can occur in middle-aged individuals" is attested by 1965 (crisis of mid-life is by 1963).

c. 1600, "under misapprehension, having made a mistake," past-participle adjective from mistake (v.). Meaning "misunderstood" is from 1590s; that of "erroneous, incorrect" is from 1670s. Related: Mistakenly. Mistaken identity in criminal cases is attested by 1838.

c. 1400, "strange style of dress" (especially one meant to deceive), from disguise (v.). Meaning "false or misleading appearance, something that serves or is intended for concealment of identity" is from 1630s. Disguisement in this sense is from 1570s but now is disused.

early 14c., "wanting vigor or energy," from lust (n.) + -less. From 1580s as "wanting sexual appetite."

1790, "one who maintains the doctrine of sexes in plants;" see sexual in the original sense + -ist.

island off Massachusetts, early forms include Natocke, Nantican, Nautican; from an obscure southern New England Algonquian word, perhaps meaning "in the middle of waters." Its identity as a summer resort for the wealthy dates to 1950s. Related: Nantucketer.

1834, "indiscriminate mixture, confusion," from French promiscuité (1752), from Latin promiscuus "mixed, not separated" (see promiscuous) + French -ité (see -ity). By 1844 in the sense of "promiscuous sexual union" (originally as among races of people). An earlier word was promiscuousness (by 1773 general; 1808 sexual).