AT ONCE


Meaning of AT ONCE in English

adverb

Etymology: Middle English at ones, from at + ones once

1.

a. : at the same time : simultaneously

the two events happened at once

b. : immediately

don't delay; do your work at once

2. : in one and the same way, manner, degree, or condition

a plan that is at once stupid and dangerous

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.