The term 'not bright' can be described by a variety of words, such as DULL, DIM, GRIM, SLOW, DENSE, DREARY, MOROSE, FATUOUS, and UNPROMISING. These words all describe someone or something that is not particularly intelligent, lively, or cheerful. DULL implies a lack of interest or enthusiasm, DIM suggests a lack of understanding or insight, GRIM implies a lack of cheerfulness or optimism, SLOW implies a lack of quickness or agility, DENSE implies a lack of intelligence or comprehension, DREARY implies a lack of joy or pleasure, MOROSE implies a lack of cheerfulness or good humor, FATUOUS implies a lack of intelligence or common sense, and UNPROMISING implies a lack of potential or success.