third base
US /ˈθɜːrd ˌbeɪs/
UK /ˈθɜːrd ˌbeɪs/

1.
the base in baseball that a runner must reach after second base and before scoring a run
:
•
The runner slid safely into third base.
•
He hit a double and advanced to third base on an error.
2.
(slang) the third stage of sexual intimacy, typically involving oral sex or manual stimulation, but not intercourse
:
•
They reached third base on their second date.
•
He was hoping to get to third base, but she wasn't ready.