"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.).
1540s, "act of converting from jealousy or suspicion and gaining favor or good will," from French conciliation, from Latin conciliationem (nominative conciliatio) "a connection, union, bond," figuratively "a making friendly, gaining over," noun of action from past-participle stem of conciliare "to bring together, unite in feelings, make friendly" (see conciliate).
mid-14c., reconcilen, transitive, in reference to persons, "to restore to union and friendship after estrangement or variance," also of God or Christ, "restore (mankind, sinners) to favor or grace," from Old French reconcilier (12c.) and directly from Latin reconcilare "to bring together again; regain; win over again, conciliate," from re- "again" (see re-) + conciliare "make friendly" (see conciliate).
Reflexive sense of "become reconciled, reconcile oneself" is from late 14c. Meaning "to make (discordant facts or statements) consistent, rid of apparent discrepancies" is from 1550s. Mental sense of "make (actions, facts, conditions, etc.) consistent with each other in one's mind" is from 1620s. Sense of "bring into acquiescence or quiet submission" (with to) is from c. 1600. Related: Reconciled; reconciling.
It forms all or part of: acclaim; acclamation; Aufklarung; calendar; chiaroscuro; claim; Claire; clairvoyance; clairvoyant; clamor; Clara; claret; clarify; clarinet; clarion; clarity; class; clear; cledonism; conciliate; conciliation; council; declaim; declare; disclaim; ecclesiastic; eclair; exclaim; glair; hale (v.); halyard; intercalate; haul; keelhaul; low (v.); nomenclature; paraclete; proclaim; reclaim; reconcile.
It is the hypothetical source of/evidence for its existence is provided by: Sanskrit usakala "cock," literally "dawn-calling;" Latin calare "to announce solemnly, call out," clamare "to cry out, shout, proclaim;" Middle Irish cailech "cock;" Greek kalein "to call," kelados "noise," kledon "report, fame;" Old High German halan "to call;" Old English hlowan "to low, make a noise like a cow;" Lithuanian kalba "language."
c. 1200, impersonal, hit semeth (it seems), "it appears (that something is so);" also with adjectives or phrases, "to appear to be (in some condition), have or present an appearance of being," from Old Norse soema "to honor; to put up with; to conform to (the world, etc.)," a verb derived from the adjective soemr "fitting."
This is reconstructed to be from Proto-Germanic *somiz (source also of Old English som "agreement, reconciliation," seman "to conciliate," source of Middle English semen "to settle a dispute," literally "to make one;" Old Danish söme "to be proper or seemly"), from PIE *somi-, suffixed form of root *sem- (1) "one; as one, together with" (also compare same).
With other verbs (seem to be, etc.) from c. 1200. Sense of "appear to oneself, think oneself" is from 1630s. Also in Middle English "to present oneself, appear; be visible, be apparent" (late 14c.), hence, of a fact, etc., "be evident, apparent, or obvious." The sense of "be fitting or appropriate, be expedient" (c. 1300) is the etymological one, but it is obsolete except in derived seemly, unseemly. Related: Seemed; seeming.