at once

adverb3

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.
2. •
   Immediately; now; right away.

   • Tell the doctor to come at once. She is having a baby.
3. •
   (no longer used) 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. — 1526