at once
Without any delay
At once means immediately, without delay: Come here at once!
It also means simultaneously, all together: Everyone started talking at once.
The two senses rarely cause confusion—context makes clear whether urgency or simultaneity is meant.
She was at once relieved and disappointed uses the simultaneous sense for mixed emotions.
Without any pause
- right awayWithout pause or delay
- straightawayWithout pause or hesitation
- promptlyWithout hesitation or delay
- nowThe present moment
directly · forthwith · without delay · posthaste · pronto · in a flash · in no time · in a jiffy
In one collective action
- concurrentlyAt the same time
- in unisonAt the same moment
- as oneIn complete agreement
- in syncMoving in unison
synchronously · in tandem · in parallel · in concert · together · jointly · collectively · side by side
instantly
Without any pause
- right awayWithout pause or delay
- straightawayWithout pause or hesitation
- promptlyWithout hesitation or delay
now · directly · forthwith · without delay · posthaste · pronto · in a flash · in no time · in a jiffy · urgently
all together
In one collective action
- concurrentlyAt the same time
- in unisonAt the same moment
- as oneIn complete agreement
in sync · synchronously · in tandem · in parallel · in concert · together · jointly · collectively · side by side · en masse
- time expressionsnow, today, soon, tomorrow, later
- instantlysuddenly, instantly, abruptly, in a flash, in an instant
- suddennesssudden, suddenly, abrupt, abruptly, instant
- parallel thingsparallel lines, side by side, abreast, tracks, twin
- affirmativesyes, yeah, yep, yup, absolutely
- phrasesnoun phrases, noun phrase, verb phrase, prepositional phrase, prepositional phrases
at oncelater
At a subsequent time
eventually · sooner or later · whenever · in time · at some point
at onceone at a time
In single succession
separately · sequentially · in turn · one by one · consecutively