once (adv.) 1
once and for all, in a word
Cor II.iii.1 [First Citizen to other Citizens, of Coriolanus] Once, if he do require our voices, we ought not to deny him
H8 I.ii.82 [Wolsey to King Henry] What we oft do best, / By sick interpreters, once weak ones, is / Not ours, or not allowed [debated text]
KJ I.i.74 [Bastard to King John, of Robert Faulconbridge] But once he slandered me with bastardy [or: on one occasion]
MA I.i.297 [Don Pedro to Claudio] 'Tis once, thou lovest
MA V.i.200 [Dogberry to Borachio or Conrade] an you be a cursing hypocrite once
See also...
Discourse markers