collab /kəˈlæb/noun 1verb 1forms 6 noun1 •(informal) A collaboration, especially a work produced by several musicians who do not usually work together.UMISEA is a subunit in Hololive featuring idols with nautical themes. The group debuted in 2021 as the first JP+EN collab subunit. Chloe was added to the roster after holox debuted. — 2023 verb1 •(informal) To collaborate. formscollabbed · collabed · collabbing · collabing · collabs · collabs.