last drink of sake; final cup
Polite term used in drinking contexts, especially when pouring the last serving of sake for a guest or companion. Often part of the phrase お積りをどうぞ (please have the last drink).
Let's call it a night. Please have the last drink.
Could you pour me the last cup?
Derived from the honorific prefix お (o-) attached to 積り (tsumori), which originally means 'accumulation' or 'intention'. In this context, it refers to the final drink that 'rounds off' a drinking session. The exact historical shift to this specialized meaning is uncertain.