noun
one cup of sake
Literally one cup of sake; often used in the context of offering or sharing a drink.
まずは一献いかがですか。
How about a cup of sake to start with?
noun
a drink; small drinking party
By extension, refers to going out for a drink or treating someone to a drink; often implies a casual, small gathering over alcohol.
Shall we go for a drink tonight?
彼を一献に誘った。
I invited him out for a drink.