at once

adv

Etymology: From Middle English at ones, equivalent to at + once.

1. At the same time; simultaneously; together.

   “Can you pat your head and rub your belly at once? He tried to eat four cookies at once.”

   “The [Washington] Post's proprietor through those turbulent [Watergate] days, Katharine Graham, held a double place in Washington’s hierarchy: at once regal Georgetown hostess and scrappy newshound, ready to hold the establishment to account.”

2. Immediately; now; right away.

   “Tell the doctor to come at once. She is having a baby.”

   “Mr. Cooke at once began a tirade against the residents of Asquith for permitting a sandy and generally disgraceful condition of the roads. So roundly did he vituperate the inn management in particular, and with such a loud flow of words, that I trembled lest he should be heard on the veranda.”

3. In one group; together.

   “And they all atonce begane to make excuſe. The fyrſt ſayd vnto him: I have bought a ferme / and I muſt nedes goo and ſe it / I praye the have me excuſed.”

   “Now if it ſo be that it woulde happely be thought not a thyng metely to be aduentured to ſet all on a fluſhe at ones, and daſhe raſhelye out holye ſcrypture in euerye lewde felowes teeth: […]”