fatigue: [17] In English a relatively formal term, fatigue goes back ultimately to a Latin expression roughly equivalent to the English notion of having ‘had it up to here’. It was borrowed from French fatiguer, a descendant of Latin fatigāre ‘tire’. This appears to have been related to the adverb affatim ‘sufficiently’, suggesting that underlying fatigāre was the idea of having ‘had enough’. The derivative indefatigable ‘tireless’ [16] comes from Latin indēfatigābilis. [fatigue etymology, fatigue origin, 英语词源]