(intransitive) To come together; to meet; to unite.

(intransitive) To come together, as in one body or for a public purpose; to meet; to assemble.

(transitive) To cause to assemble; to call together; to convoke.

(transitive) To summon judicially to meet or appear.

(transitive, with "on" or "upon") To make a convention; to declare a rule by convention.