WordReference Random House Learner's Dictionary of American English © 2026
si•mul•ta•ne•ous /ˌsaɪməlˈteɪniəs, ˌsɪməl-/USA pronunciation
adj.
WordReference Random House Unabridged Dictionary of American English © 2026- existing, occurring, or operating at the same time:simultaneous translation of all speeches at the United Nations.
si•mul•ta•ne•ous
(sī′məl tā′nē əs, sim′əl-),USA pronunciation adj.
si′mul•ta′ne•ous•ly, adv.
si′mul•ta′ne•ous•ness si•mul•ta•ne•i•ty
(sī′məl tə nē′i tē, sim′əl-),USA pronunciation n.
- existing, occurring, or operating at the same time; concurrent:simultaneous movements; simultaneous translation.
- Latin simul together (see similar) + (instan)taneous
- 1650–60
- synchronous, coincident.
'simultaneously' also found in these entries (note: many are not synonyms or translations):
AND circuit
- AWACS
- Newton's laws of motion
- acciaccatura
- ambivalence
- arpeggio
- autodyne
- breaststroke
- breath
- broadband
- capo
- central locking
- chord
- chorus
- co-edition
- co-occur
- cognitive dissonance
- coincide
- combine harvester
- complementarity principle
- concur
- concurrence
- concurrent
- conference call
- coseismal
- cotransduction
- countereconomy
- countermelody
- countersubject
- cross-addicted
- cross-fade
- crow's-foot
- daisy chain
- decay
- diagonal
- diplophonia
- direct mail
- dissolve
- double dribble
- double fugue
- double stop
- double-stop
- douzaine
- electrocautery
- epidemic
- family therapy
- feeder
- fire
- fireworks
- flashgun