Main Entry: go in

Function: intransitive verb

Date: 1812

1 : to make an approach (as in attacking)
2 a : to take part in a game or contest b : to call the opening bet in poker : stay
3 of a celestial body : to become obscured by a cloud
4 : to form a union or alliance : join —often used with with <asked us to go in with them>

— go in for 1 : to give support to : advocate
2 : to have or show an interest in or a liking for
3 : to engage in : take part in