c.1300, "meeting of adversaries, confrontation," from Old French encontre "meeting; fight; opportunity" (12c.), noun use of preposition/adverb encontre "against, counter to" from Late Latin incontra "in front of," from Latin in- "in" (see in-(2)) + contra "against" (see contra). Modern use of the word in psychology is from 1967, from the work of U.S. psychologist Carl Rogers (1902-1987). Encounter group attested from 1967.

c.1300, "to meet as an adversary," from Old French encontrer "meet, come across; confront, fight, oppose," from encontre (see encounter, n.). Weakened sense of "meet casually or unexpectedly" first recorded in English early 16c. Related: Encountered; encountering.