at once

1. сейчас же

2. сразу; немедленно

this once, just for once — хотя бы раз; только в этой связи

the army at once fell in pieces — армия сразу же распалась

do it but this once — сделайте это хотя бы на этот раз

you must pay at once — вы должны заплатить немедленно

I must clear out at once — я должен немедленно уехать

Синонимический ряд:

1. at the same time (adj.) at the same time; concurrently; contemporaneously; parallel; together

2. immediately (adj.) directly; immediately; instantly; now; right away; without delay

3. away (other) away; directly; first off; forthwith; immediately; instanter; instantly; now; PDQ; right; right away; right off; straight; straight away; straight off; straightway

4. together (other) coincidentally; coincidently; coinstantaneously; concurrently; simultaneously; together