verb (used without object), col·lab·o·rat·ed, col·lab·o·rat·ing.
1.
to work, one with another; cooperate, as on a literary work: They collaborated on a novel.
2.
to cooperate, usually willingly, with an enemy nation, especially with an enemy occupying one's country: He collaborated with the Nazis during World War II.
Origin: 1870–75; < Late Latin collabōrātus (past participle of collabōrāre), equivalent to col-col-1 + labor work + -ātus-ate1