Dullness

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)