43 synonyms for at the same time such as anyhow, all together, after everything, and all the same. At the same time is an adverb, and its antonyms are separately and consecutively.
All together, alongside each other, as a group, at once, at one and the same time, at one time, at the same instant/moment, concomitantly, concurrently, in chorus, in concert, in unison, simultaneously, synchronously, and together.
After everything, all the same, anyhow, anyway, at any rate, be that as it may, but, come what may, despite that/everything, even so, for all that, having said that, howbeit, however, in any event, in spite of that/everything, just the same, natheless, nevertheless, nonetheless, notwithstanding, regardless, still, still and all, though, withal, and yet.