The DEFinition received a mild reception from music critics, saying that it was better than 2002's 10 because of Timbaland's production. At Metacritic, which assigns a normalized rating out of 100 to reviews from mainstream critics, the album received an average score of 66, based on 9 reviews.
Steve 'Flash' Juon of RapReviews called The DEFinition LL's "TRUE tenth album," praising its change in sound from New York to Southern by Timbaland, balancing out the bangers and slow songs well and LL for still keeping his lyrical content up to date, concluding that "this new album proves he doesn't have to give up acting to keep rapping."AllMusic's David Jeffries said that the album had more energy than 10 because of Timbaland's take on the southern sound and finding a balance between braggadocious rap and lovers rap. Gavin Edwards of Rolling Stone also praised the production for updating LL's sound along with his lyrics, saying that "on the eleventh record of his amazingly consistent twenty-year career, LL Cool J has as much swaggering presence as ever." Nick Southall of Stylus Magazine was mixed about the album, saying that he enjoyed the love jams better than the Timbaland bangers which were merely passable, concluding that "there's a distinct lack of personality, meaning that LL Cool J's eleventh long player is merely good, and his reputation (and bank balance) will be neither tarnished nor expanded."