all at once

all at once  {adv. phr.}
1. At the same time; together.
The teacher told the children to talk one at a time; if they all talked at one time, she could not understand them.
Bill can play the piano, sing, and lead his orchestra all at once.
Without warning; abruptly; suddenly; unexpectedly.
All at once we heard a shot and the soldier fell to the ground.
All of a sudden the ship struck a rock.
Compare: AT ONCE.
Categories: time {adv. phr.}