fatigue (n.) Look up fatigue at Dictionary.com
1660s, "that which causes weariness," from French fatigue "weariness," from fatiguer "to tire" (15c.), from Latin fatigare "to weary, to tire out," originally "to cause to break down," from pre-Latin adjective *fati-agos "driving to the point of breakdown," with first half from Old Latin *fatis, which is of unknown origin but apparently related to affatim (adv.) "sufficiently" and to fatisci "crack, split." The second half is the root of agere "to drive" (see act (n.)).

Especially "the labors of military persons" (1776). Meaning "a feeling of weariness from exertion" is from 1719. Of metals or other materials under strain, from 1877.
fatigue (v.) Look up fatigue at Dictionary.com
1690s, from French fatiguer "to tire" (15c.), from fatigue (see fatigue (n.)). Earlier in same sense was fatigate (1530s), from Latin fatigatus, past participle of fatigare. Related: Fatigued; fatiguing; fatigation (c.1500).