"reverse or remove conditioned reflexes from," 1914, from de- "do the opposite of" + condition (v.). Related: Deconditioned; deconditioning.

also turnaround, 1936, from verbal phrase turn around "reverse," 1880, American English, from turn (v.) + around (adv.).

"to render unfit," 1610s, from unfit (adj.), or else from un- (2) "reverse of" + fit (v.). Related: Unfitted; unfitting.

"deprive of the qualities considered typical of one's gender," c. 1600, from un- (2) "reverse, opposite of" + sex (n.). Related: Unsexed; unsexing.

1808, transitive, "undo the articulation of, separate joint from joint;" see dis- "reverse, opposite of" + articulate (v.). Intransitive sense of "become separated, lose articulation" is by 1830. Related: Disarticulated; disarticulating.

late 15c., from un- (2) "reverse, opposite of" + pack (v.). Similar formation in Dutch ontpakken. Related: Unpacked; unpacking.

1590s, "undo from a fixed position," from un- (2) "reverse, opposite of" + settle (v.). Of the mind, feelings, etc., attested from 1640s. Related: Unsettled; unsettling.

1620s, "to destroy the strength of," from un- (2) "reverse, opposite of" + nerve (v.). Meaning "to deprive of courage" is recorded from 1704. Related: Unnerved; unnerving.

"deprive of contentment, late 15c., from dis- "not, reverse of" + content (v.). Perhaps from Old French descontenter. Related: Discontented; discontentedly; discontentment; discontentedness.

"to turn (something) in an opposite direction; reverse the position, order, or sequence of," 1530s, from French invertir or directly from Latin invertere "turn upside down, turn about; upset, reverse, transpose," figuratively "pervert, corrupt, misrepresent," of words, "to use ironically," from in- "in, on" (from PIE root *en "in") + vertere "to turn" (from PIE root *wer- (2) "to turn, bend"). Related: Inverted; inverting; invertedly.