有分別作用之意。對於無分別而言。六識中眼等五識，唯有尋伺相應之自性分別，故俱舍論二，名之為無分別，第六意識，並具散慧相應之計度分別及定散諸念之隨念分別，能分別所緣之境，故名之為有分別。成唯識論七亦曰：「於彼所緣能明了取，異於眼等識，故非無用，由此聖教說彼意識名有分別。」又對於無分別正體智而名其餘後得等智為有分別。即緣境分別種種之差別智也。
The sixth sense of mental discrimination manas, as contrasted with the other five senses, sight, hearing, etc., each of which deals only with its own perceptions, and is 無分別.