Join v. t. : To bring together, literally or figuratively; to place in contact; to connect; to couple; to unite; to combine; to associate; to add; to append.

Join v. t. : To associate one's self to; to be or become connected with; to league one's self with; to unite with; as, to join a party; to join the church.

Join v. t. : To unite in marriage.

Join v. t. : To enjoin upon; to command.

Join v. t. : To accept, or engage in, as a contest; as, to join encounter, battle, issue.

Join v. i. : To be contiguous, close, or in contact; to come together; to unite; to mingle; to form a union; as, the hones of the skull join; two rivers join.

Join n. : The line joining two points; the point common to two intersecting lines.

Example:
i want to Join a nonprofit volunteer organization, where do i start?

Taxonomy
employee, predicate, relation, outer joins, LastName, John, Engineering, Clerical, Smith, EmployeeID, Employee Table, Rafferty, Jones, Steinberg, employee RIGHT, Marketing, Country, Robinson.

Defination from the web:
JOIN predicate to identify the records for joining. ... All subsequent explanations on join types in this article make use of the following two tables. The rows in these tables serve to illustrate the effect of different types of joins and join-predicates. ...