All at once
- (idiomatic) Unexpectedly; without warning; all of a sudden.
- When all at once I saw a crowd, A host, of golden daffodils - William Wordsworth, Daffodils
- Used other than as an idiom: All at the same time; all together.
- There are too many to get in the lift all at once, so some must wait.
abruptly; all together; at a blow; at a stroke; at once; at one blow; at one jump; at one stroke; at one swoop; at one time; bang; collectively; communally; conjointly; corporately; dash; en masse; ensemble; forthwith; hastily; impetuously; impulsively; in a body; in a hurry; in association; in company; in conjunction; jointly; like a flash; like a thunderbolt; mutually; now; of a sudden; on short notice; per saltum; plop; plump; plunk; pop; precipitantly; precipitately; precipitously; pronto; right away; right now; right off; sharp; simultaneously; slap; smack; startlingly; straightaway; straightway; subito; sudden; suddenly; surprisingly; then and there; this minute; this very minute; together; unawares; unexpectedly; unitedly; uno saltu; without delay; without notice; without warning