go out

to leave a room or building, especially in order to do something for entertainment:
Please close the door as you go out.
Do you want to go out for a drink after work?
It's terribly smoky in here - I'm just going out for a breath of fresh air.
[ + -ing verb ] She goes out partying with her friends every weekend.
She likes to go out at the weekend.
I'm just going out for a walk. Do you want to come?
What time do you want to go out?
Tony forgot to take an umbrella when he went out. I hope it doesn't rain.
He's just gone out. Can I take a message?

to have a romantic and usually sexual relationship with someone:
How long have you been going out with him?
They'd been going out (together/with each other) for almost five years before he moved in with her.

If the tide goes out, it moves back and covers less of the beach.

If a light or something that is burning goes out, it stops producing light or heat:
When I woke up the fire had gone out.

UK
to lose when you are playing in a sports competition, so that you must stop playing in the competition:
England went out to France in the second round of the championship.
(Cambridge Advanced Learner's Dictionary & Thesaurus からの go out の定義 © Cambridge University Press)

アメリカ英語辞典
to have a romantic relationship, esp. one that includes going places together:
We’ve been going out for five months.

(of the ocean tide) to be flowing to a lower level:
While we were gone the tide had gone out, leaving our boat sitting on a sandbar.
(Cambridge Academic Content Dictionary からの go out の定義 © Cambridge University Press)

- Cambridge Dictionary