godan verb (-su), transitive verb
leave undrunk; not finish a drink
Used when someone does not finish a beverage, leaving some remaining in the glass or container.
彼はコーヒーを飲み残して席を立った。
He left his coffee undrunk and stood up.
子供は牛乳をいつも飲み残す。
The child always leaves some milk undrunk.