Definitions
1.AdverbOne and only one time."I have only once eaten pizza."
2.AdverbFormerly; during some period in the past."He was once the most handsome man around.; I once had a motorbicycle.; Once I didn't drive a big car, but now I own an all-terrain 4WD.; Wang notes that flowers have rooted and grow in the area once covered with ice."
3.AdverbAt any time; ever."If the facts once became known, we'd be in trouble."
4.AdverbOne day, someday.
5.AdverbMultiplied by one: indicating that a number is multiplied by one."Once three is three."
6.ConjunctionAs soon as; when; after."We'll get a move on once we find the damn car keys!; Once you have obtained the elven bow, return to the troll bridge and trade it for the sleeping potion.; Once he is married, he will be able to claim the inheritance."
7.NounObsolete form of ounce.