Dullness may refer to:
In vision A lack of perceived brightness A lack of perceived colorfulness
In medicine A dull sound in response to percussion (medicine) Shifting dullness, a medical sign
In philosophy and religion Tamas (philosophy), one of the three tendencies in the Samkhya school of Hindu philosophy Thīna, an unwholesome mental factor in Buddhism Laya or bying-ba, in the five faults and eight antidotes of Tibetan Buddhism
Other uses Dulling, the tendency of a blade to lose sharpness Stupidity A tendency to cause boredom Drowsiness (archaic)
See also Dull (disambiguation) Dulness, a goddess in The Dunciad Dully, a municipality in the canton of Vaud in Switzerland