Things which are simultaneous happen or exist at the same time.
...the simultaneous release of the book and the album.
The theatre will provide simultaneous translation in both English and Chinese.
Synonyms: coinciding, parallel, concurrent, synchronized
simultaneously adverb [ADVERB with verb] B2 The two guns fired almost simultaneously.
He ran the mighty Chicago Symphony Orchestra simultaneously with the State Opera House in Berlin.
Synonyms: at the same time, together, all together, in concert