reacted

Reacted is the past tense and past participle of the verb react. In general usage, to react means to respond to a stimulus, situation, or input. For example, one might say, “She reacted with surprise to the news.” In scientific contexts, react refers to a chemical or physical interaction, as in, “The substances reacted to form a precipitate,” or “The solution reacted with the acid.” The past tense is used for completed actions or in passive constructions: “The mixture was heated and then reacted with chlorine.”

Etymology and related forms: React comes from the Latin reactus, formed from re- meaning back or again and agere, to drive or act. English inherited the term through other European languages as it developed into a general verb for response. Related words include reaction (noun), reactive (adjective), and reactor or reactor systems in technical fields.

Usage notes: In grammar, react can be intransitive, meaning to respond in general, or transitive when there is a direct object related to the response or a chemical change, as in “to react a substance with another.” Common collocations include react to something, react positively or negatively, and react with a reagent. The word appears across everyday language, psychology and sociology discussions, and natural and physical sciences to describe responses or interactions.

See also: reaction, reactive, reaction rate, chemical equation.