noun
Refers to something one needs to do or take care of, often outside the home. Common in phrases like 用がある, 用を足す, and 用事.
ちょっと用があって、出かけてきます。
I have a quick errand to run, so I'll be out for a bit.
今日は特に用はない。
I don't have anything in particular to do today.
noun
Indicates what something is used for or its intended purpose. Often appears in compounds like 使い道 or 用途, but can stand alone.
この道具の用を教えてください。
Please tell me the use of this tool.
この箱は何の用に使うのですか。
What is this box used for?
noun, used as a suffix
for ... use; used for ...; made for ...
Suffix attached to nouns to indicate something is intended for a specific purpose or user. Very productive in everyday Japanese.
これは子供用の椅子です。
This is a chair for children.
非常用の食料を備蓄している。
We stockpile food for emergency use.
noun
call of nature; excretion
Euphemistic use, almost always in the set phrase 用を足す (to relieve oneself). Rarely used outside this expression.
See also: 用を足す
ちょっと用を足してきます。
I'm going to go to the bathroom.