needn't've

Verb

need not (third-person singular simple present need not, no present participle, simple past needed not, no past participle)

1. (UK, auxiliary, no-past-participle, no-present-participle) Indicating absence of necessity; needn't, do(es) not have to, do(es) not need to.
   • My example illustrates how circularity can arise in arguments that appeal to experiment. But the very same example serves to show that this need not be the case.2013, Alan Chalmers, What is this thing called Science?, University of Queensland Press, page 36

   Synonyms:

   not have to, needn't

2. (auxiliary, dated, no-past-participle, no-present-participle) Indicating inadvisability; ought not to.
   • Want ads for what little manual labor there was frequently had the stipulation INNA, an acronym for Italians and Irish Need Not Apply.2018 June 1, Gerard Letterie, “Education is the beacon that lights our path forward in America”, in The Seattle Times