thumbs up noun 2thumbs-up verb 1forms 4 noun2 •A gesture signifying approval or okay; a thumb pointing up out of a fist.He smiled and gave a big thumbs up. •(figurative) An approval or OK.We got the thumbs up to go ahead with the project. thumbs-up verb1 •To approve with a thumbs-up sign.He stood outside the dressing room and thumbs-upped or thumbs-downed each choice. — 2015 formsthumbs-upped · thumbs-upping · thumbs-ups · thumbs ups