Duration

google

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late Middle English: via Old French from medieval Latin duratio(n- ), from durare ‘to last’, from durus ‘hard’.

wiktionary

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From Middle English duracioun, from late Old French duracion, from Medieval Latin dūrātiō.

etymonline

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duration (n.)

"continuance in time; length of time during which anything continues," late 14c., duracioun, from Old French duration, from Medieval Latin durationem (nominative duratio), noun of action from past-participle stem of Latin durare "to harden," from durus "hard," from PIE *dru-ro-, suffixed variant form of root *deru- "be firm, solid, steadfast." The old legalese phrase for the duration was popularized 1916 in reference to British enlistments in World War I.