fatigue

Fatigue refers to extreme physical or mental tiredness or exhaustion. (noun)

An example of fatigue is what you feel after you run a 10-mile marathon.

See fatigue in Webster's New World College Dictionary

noun

physical or mental exhaustion; weariness
the cause of this; hard work; toil
any manual labor or menial duty, other than drill or instruction, assigned to soldiers
in full fatigue duty
sturdy work clothing worn by soldiers doing fatigue duty
also fatigue clothes (or clothing)
the tendency of a metal or other material to crack and fail under repeated applications of stress
Physiol. the decreased ability to function or inability to respond of an organism or one of its parts due to prolonged exertion or repeated stimulation

transitive verb, intransitive verb fatigued, fatiguing

See fatigue in American Heritage Dictionary 4

(fə-tēgˈ)

noun

Physical or mental weariness resulting from exertion.
Something, such as tiring effort or activity, that causes weariness: the fatigue of a long hike.
Physiology The decreased capacity or complete inability of an organism, an organ, or a part to function normally because of excessive stimulation or prolonged exertion.
The weakening or failure of a material, such as metal or wood, resulting from prolonged stress.
a. Manual or menial labor, such as barracks cleaning, assigned to soldiers.
b. fatigues Clothing worn by military personnel for labor or for field duty.