1827, "to handle skillfully by hand," a back-formation from manipulation. As "to manage by mental influence," especially for one's own purposes, is by 1864. Financial sense is from 1870. By 1949 it served as a euphemism for "masturbate." Related: Manipulated; manipulating.
"one who manipulates" in any sense, 1804, agent noun from manipulate, perhaps on model of French manipulateur (1783). Related: Manipulatory.
"apply massage to, treat by means of massage," 1874, from massage (n.). Figurative sense of "manipulate" (data, etc.) is by 1966. Related: Massaged; massaging.
"impose (something) on (someone) by fraud," 1670s, from palm (n.1); around the same time it also meant "conceal in the palm of the hand" (1670s) and "handle, manipulate" (1680s). Extended form palm off (something, on someone) is from 1822.
1520s, "something that frightens, a scarecrow;" 1540s, "sudden panic, sudden terror inspired by a trifling cause, false alarm," from scare (v.). The earlier form was Middle English sker "fear, dread, terror, fright" (c. 1400). Scare tactic "attempt to manipulate public opinion by exploitation of fear" is by 1948.
Old English cnedan "to knead, manipulate by squeezing or pressing," from Proto-Germanic *knedan (source also of Old Saxon knedan, Middle Dutch cneden, Dutch kneden, Old High German knetan, German kneten, Old Norse knoða "to knead"). Originally a strong verb (past tense cnæd, past participle cneden). For pronunciation, see kn-. The evolution of the vowel is unusual. Related: Kneaded; kneading.
1722, "anything with which one amuses oneself, a harmless frolic," Scottish and northern England dialect, possibly a shortened form of employ. Popularized in the sense of "move or gambit made to manipulate others and gain advantage" by British humorist Stephen Potter (1900-1969), who parodied self-help manuals in books such as 1947's "The Theory and Practice of Gamesmanship: Or the Art of Winning Games Without Actually Cheating."
"to discipline, teach, bring to a desired state by means of instruction," 1540s, probably from earlier sense of "draw out and manipulate in order to bring to a desired form" (late 14c.), specifically of the growth of branches, vines, etc. from mid-15c.; from train (n.). Sense of "point or aim" (a firearm, etc.) is from 1841. Sense of "fit oneself for a performance by a regimen or exercise" is from 1832. The meaning "to travel by railway" is recorded from 1856. Related: Trained; training.