1. (a.) Accompanying; existing concurrently; as, concominant plans\.

2. (n.) One who, or that which, accompanies, or is collaterally connected with another; a companion; an associate; an accompaniment.

accession accessory accompaniment accompanying accordant addenda addendum additament addition additive additory additum adjunct adjuvant agreeing annex annexation appanage appendage appendant appurtenance appurtenant associate associated at one with attachment attendant attending augment augmentation coacting coactive coadunate coda coetaneous coeternal coeval coexistent coexisting coincident coinstantaneous collaborative collateral collective collusive combined combining companion complement concerted concordant concurrent concurring conjoint consilient consort conspiratorial contemporaneous contemporary conterminous continuation cooperant cooperative coordinate corollary correlative coterminous coupled coworking dead heat draw extension extrapolation fellow fixture harmonious increase increment isochronal isochronous joined joint mate meeting mutual offshoot paired parallel parasitic pendant reinforcement saprophytic side effect side issue simultaneous supplement symbiotic synchronous synergetic synergic synergistic tailpiece tie twin undergirding unison unisonous united uniting