The term LEAST BRIGHT is used to describe something that is not very bright or luminous. The crossword solutions for this term are DENSEST (7 letters), PALEST (6 letters), and DIMMEST (7 letters). DENSEST refers to something that is very dense or thick, PALEST refers to something that is very pale or light in color, and DIMMEST refers to something that is very dim or faint. All three of these words can be used to describe something that is not very bright or luminous.