Definition of "join" in Essential American English Dictionary

join

verb us /dʒɔɪn/

A2 to become a member of an organization:

He joined the army when he was 18.

A2 to do something or go somewhere with someone:

Would you like to join us for dinner?

B1 to fasten or connect things together:

Join the ends together with glue.

B1 to meet at a particular point:

This is the point where the two rivers join.

(Definition of “join” from the Webster's Essential Mini Dictionary © Cambridge University Press)