jointly

conjointly, mutually, together, combined, in common, in federation, in unison, in conjunction, in partnership, in concert, in alliance, in association, in league, in combination, connectedly, unitedly, federally, co-operatively, corporately, harmoniously, reciprocally, inseparably, with mutual reliance, concomitantly, companionably, hand in hand, hand in glove, collectively, in a body, with one accord, with one assent, in company with, arm in arm, side by side, en masse, in a group, in ensemble, as one, with one another, agreeably, simultaneously, coincidentally, synchronically, concurrently, inextricably, contemporaneously, cheek by jowl*, in cahoots*.

Antonyms singly*, separately*, severally.