[transitive, intransitive] to fix or connect two or more things together. join A to/onto B Join one section of pipe to the next.

to work together in order to achieve a shared aim The two firms joined forces to win the contract. join hands (with somebody).

connection. ​a place where two things are fixed together. The two pieces were stuck together so well that you could hardly see the join.

a place where two things are fixed together. The two pieces were stuck together so well that you could hardly see the join.

The earliest known use of the noun join is in the 1820s. OED's earliest evidence for join is from 1825, in the writing of E. Hewlett.

to take part in an activity with other people She listens but she never joins in. I wish he would join in with the other kids. Want to learn more?

There are 38 meanings listed in OED's entry for the verb join, nine of which are labelled obsolete. See 'Meaning & use' for definitions, usage, and quotation ...

​to take part in an activity with other people. She listens but she never joins in. I wish he would join in with the other children. Everyone joined in with ...

join up (with somebody) ... to combine with someone else to do something We'll join up with the other groups later.

phrasal verb. join up. ​to become a member of the armed forces synonym enlist. Her grandfather joined up in 1914.