From Longman Dictionary of Contemporary Englishstag nightˈstag night noun [countable] British EnglishMARRY a night before a man’s wedding, which he spends with his male friends, drinking or having a party
Examples from the Corpus
stag night• Two mornings ago David Gower and his stag night team-mates were groaning under their bedcovers.• The tough rugby player at first put the pain of his acute appendicitis down to the after-effects of his stag night.• He sat shame-faced as a court heard that his career was in tatters because of the stag night brawl.• The operation came to an end on 8 October 1988, when Mazur faked his own wedding stag night.• On the wedding day, he was holding his head and nudging his friends about the wild stag night they'd enjoyed. 