word-forming element meaning "together, with," sometimes merely intensive; it is the form of com- used in Latin before consonants except -b-, -p-, -l-, -m-, or -r-. In native English formations (such as costar), co- tends to be used where Latin would use con-.

*gwā-, also *gwem-, Proto-Indo-European root meaning "to go, come."

It forms all or part of: acrobat; adiabatic; advent; adventitious; adventure; amphisbaena; anabasis; avenue; base (n.) "bottom of anything;" basis; become; circumvent; come; contravene; convene; convenient; convent; conventicle; convention; coven; covenant; diabetes; ecbatic; event; eventual; hyperbaton; hypnobate; intervene; intervenient; intervention; invent; invention; inventory; juggernaut; katabatic; misadventure; parvenu; prevenient; prevent; provenance; provenience; revenant; revenue; souvenir; subvention; supervene; venire; venue; welcome.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit gamati "he goes," Avestan jamaiti "goes," Tocharian kakmu "come," Lithuanian gemu, gimti "to be born," Greek bainein "to go, walk, step," Latin venire "to come," Old English cuman "come, approach," German kommen, Gothic qiman.

late 14c., "fittingly, properly, rightly," from convenient + -ly (2). Meaning "in a way that avoids difficulty" is from c. 1500.

late 14c., "injurious, dangerous," also "absurd, illogical" (senses now obsolete), from Latin inconvenientem (nominative inconveniens) "unsuitable, not accordant, dissimilar," from in- "not, opposite of" (see in- (1)) + convenientem (see convenient). In early 15c., "inappropriate, unbecoming, unnatural;" also, of an accused person, "unlikely as a culprit, innocent." Sense of "troublesome, incommodious, awkward" is recorded from 1650s.