"in the time of, in the course of, throughout the continuance of," late 14c., duryng (earlier durand, mid-14c.), present participle of the long-obsolete verb duren "to last, endure, continue, be or exist" (mid-13c.), which is from Old French durer, from Latin durare "to harden," from durus "hard" (from PIE root *deru- "be firm, solid, steadfast"). During the day is "while the day endures," and the prepositional usage is a transference into English of a Latin ablative absolute (compare durante bello "during (literally 'enduring') the war").
updated on October 19, 2018