once once /ˈwʌns/

adverb

1. () On one occasion  ( in one case , one time , once )
   on one occasion
    Once I ran into her
   once I ran into her
   
2. () As soon as  ( once )
   as soon as
    Once we are home, we can rest
   once we are home, we can rest
   
3. () At a previous time  ( at one time , erst [Archaic] , erstwhile [Archaic] , formerly , once )
   at a previous time
    At one time he loved her
   at one time he loved her
    Her erstwhile writing
   her erstwhile writing
    She was a dancer once
   she was a dancer once