adj. /nuyt"lawng', -long'/ ; adv. /nuyt"lawng", -long"/ , adj.
1. lasting all night: a nightlong snowfall.
adv.
2. through the entire night: They typed nightlong to finish the reports.
[ bef. 1000; ME; OE nihtlang (adv.) for the space of a night. See NIGHT, LONG 1 ]