WordReference Random House Unabridged Dictionary of American English © 2025
stag′ par′ty, 
- a social gathering or outing for men only.
 - a party given a bachelor by his male friends before his marriage, often on the night before the wedding, ranging from a formal gathering to a night of carousing.
 - a gathering for men only, esp. one for the purpose of watching sexually titillating movies or exhibitions.
 - 1850–55, American.
 
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'stag party' also found in these entries (note: many are not synonyms or translations):