Meaning

adjective descriptive of any event or stimulus or process that has an effect on events or stimuli or processes that occur subsequently

adjective (of a policy or person or action) controlling a situation by causing something to happen rather than waiting to respond to it after it happens

originFrom pro- + active; originally coined 1933 by Paul Whiteley and Gerald Blankfort in a psychology paper, used in technical sense. Used in a popular context and sense (courage, perseverance) in 1946 book Man’s Search for Meaning by neuropsychiatrist Viktor Emil Frankl, in the context of dealing with the Holocaust, as contrast with reactive.

Etymology from Wiktionary, CC BY-SA 3.0