once
//wʌns//
Adverb
1
on one occasion or for one time only
I have only been to Paris once.
2
at some time in the past; formerly
This building was once a school.
3
multiplied by one; by one time (used in mathematical operations)
Two once two is two.
Synonym
Conjunction
1
as soon as; when; after
Once you finish your homework, you can go outside.
Synonym
Noun
1
a single occasion or instance
Just this once, I'll let you stay up late.