early 12c., "come into agreement," also "agree, be in harmony," from Old French acorder "agree, be in harmony" (12c.), from Vulgar Latin *accordare "make agree," literally "be of one heart, bring heart to heart," from Latin ad "to" (see ad-) + cor (genitive cordis) "heart" (used figuratively for "soul, mind"), from PIE root *kerd- "heart." Compare concord, discord. Related: Accorded; according.
early 15c., "performance of a task; state of completion," from Old French acomplissement "completion, action of accomplishing," from acomplir "to fulfill, carry out, complete" (see accomplish). Meaning "thing completed" and that of "something that completes" someone and fits him or her for cultivated or fashionable society are from c. 1600.
late 14c., "fulfill, perform, carry out an undertaking," from Old French acompliss-, present-participle stem of acomplir "to fulfill, fill up, complete" (12c., Modern French accomplir), from Vulgar Latin *accomplere, from Latin ad "to" (see ad-) + complere "to fill up," transferred to "fulfill, finish (a task)," from com-, here probably as an intensive prefix (see com-), + plere "to fill" (from PIE root *pele- (1) "to fill"). Related: Accomplished; accomplishing.
"associate in crime," 1580s, an unetymological extension of earlier complice "an associate or confederate" (early 15c.), from Old French complice "a confederate, partner" (not in a criminal sense), from Late Latin complicem (nominative complex) "partner, confederate," from Latin complicare "to involve," literally "fold together," from com "with, together" (see com-) + plicare "to fold, weave" (from PIE root *plek- "to plait"). Altered perhaps on model of accomplish, etc., or by assimilation of the indefinite article in a complice.
c. 1600, "that which supplies a want or need," from French accommodation, from Latin accommodationem (nominative accommodatio) "an adjustment," noun of action from past-participle stem of accommodare "make fit; make fit for" (see accommodate). Meaning "appliance, anything which affords aid" is from 1610s; that of "act of accommodating" is from 1640s. Meaning "arrangement of a dispute" is from 1640s. An accommodation train (1838) was one making all stops (as opposed to an expresss); it was used earlier of stages (1811).