1530s, "to cause to happen sooner," a back-formation from anticipation, or else from Latin anticipatus, past participle of anticipare "take (care of) ahead of time," literally "taking into possession beforehand," from anti, an old form of ante "before" (from PIE root *ant- "front, forehead," with derivatives meaning "in front of, before") + capere "to take," from PIE root *kap- "to grasp."
Later "prevent or preclude by prior action" (c. 1600) and "be aware of (something) coming at a future time" (1640s). Used in the sense of "expect, look forward to" since 1749, but anticipate has an element of "prepare for, forestall" that, etymologically, should prevent its being used as a synonym for expect. Related: Anticipated; anticipating.
adjective and noun suffix, "having to do with, characterized by, tending to, place for," from Middle English -orie, from Old North French -ory, -orie (Old French -oir, -oire), from Latin -orius, -oria, -orium.
Latin adjectives in -orius, according to "An Etymological Dictionary of the French Language," tended to "indicate a quality proper to the action accomplished by the agent; as oratorius from orator; laudatorius from laudator. The neuter of these adjectives was early employed as a substantive, and usually denoted the place of residence of the agent or the instrument that he uses; as praetorium from praetor; dormitorium from dormitor; auditorium, dolatorium.
"These newer words, already frequent under the Empire, became exceedingly numerous at a later time, especially in ecclesiastical and scholastic Latin; as purgatorium, refectorium, laboratorium, observatorium, &c." [transl. G.W. Kitchin, Oxford, 1878]