Coinstantaneous(a.) Happening at the same instant.
Thesaurus Entries
accessory, accidental, accordant, ado, afloat, afoot, agreeing, associate, associated, at one with, attendant, attending, circumstantial, coacting, coactive, coadunate, coetaneous, coeternal, coeval, coexistent, coexisting, coincident, coinstantaneous, collaborative, collateral, collective, collusive, combined, combining, concerted, concomitant, concordant, concurrent, concurring, conjoint, consilient, conspiratorial, contemporaneous, contemporary, conterminous, cooperant, cooperative, coordinate, correlative, coterminous, coupled, coworking, current, doing, eventuating, fellow, going on, happening, harmonious, in hand, in the wind, incidental, isochronal, isochronous, joined, joint, meeting, mutual, occasional, occurring, on, on foot, ongoing, paired, parallel, parasitic, passing, prevailing, prevalent, resultant, saprophytic, simultaneous, symbiotic, synchronous, synergetic, synergic, synergistic, taking place, twin, under way, unison, unisonous, united, uniting