manipulation is the handling or operating of something with skill — and, in the sense that now dominates ordinary use, the management of a person or a situation by unfair, insidious, or deceptive means.
The word arrived in English by 1730 as a term for a method of extracting ore, from French manipulation, from manipule, "a handful," and behind that Latin manipulus, "handful, sheaf, bundle," compounded from manus ("hand") and the root of plere ("to fill"). The literal sense of skillful handling of objects is recorded by 1826, and the sense of handling or managing persons — especially to one's own advantage — follows almost immediately, by 1828. The verb manipulate is an 1827 back-formation from the noun, initially meaning to handle by hand and shifting by 1864 to managing by mental influence.
The neutral senses have not disappeared. A surgeon manipulates tissue, a physical therapist manipulates a joint, a statistician manipulates data, and none of these carries any imputation of bad faith. The pejorative reading is strong enough that the neutral uses now generally require a context that supplies the innocence — which is itself evidence of how completely the interpersonal sense has taken over the bare word.
The distinction that matters most is between manipulation and persuasion. Persuasion works through reasons the other person can inspect, weigh, and reject; manipulation works by concealing the reason, exploiting a known bias, or misrepresenting the stakes, and so bypasses judgment rather than engaging it. That test — can the target see what is being done to them and still decline? — is what separates negotiation from exploitation regardless of outcome. Manipulation also differs from coercion, which operates through overt threat and does not depend on concealment at all. Named patterns such as 📝gaslighting and 📝coercive control describe specific, sustained forms it takes in close relationships, where the cumulative effect is a loss of autonomy and of the mutual 📝trust that makes accurate perception of the relationship possible.