"tending to conciliate," 1570s, from conciliate + -ory. Related: Conciliator "one who conciliates" (1570s). Conciliative "designed to produce conciliation" is attested from 1817.
Entries linking to conciliatory
conciliate v.
"overcome distrust or hostility of by soothing and pacifying," 1540s, from Latin conciliatus, past participle of conciliare "to bring together, unite in feelings, make friendly," from concilium "a meeting, a gathering of people," from assimilated form of com "together, together with" (see com-) + PIE *kal-yo-, suffixed form of root *kele- (2) "to shout" (the notion is of "a calling together"). Related: Conciliated; conciliating; conciliary. The earlier verb was Middle English concile "to reconcile" (late 14c.).
-ory
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]