Until

conjunction
1.
up to the time that or when; till:
He read until his guests arrived.
2.
before (usually used in negative constructions):
They did not come until the meeting was half over.
preposition
3.
onward to or till (a specified time or occurrence):
She worked until 6 p.m.
4.
before (usually used in negative constructions):
He did not go until night.
5.
Scot. and North England. to; unto.
conjunction (subordinating)
1.
up to (a time) that: he laughed until he cried
2.
(used with a negative) before (a time or event): until you change, you can’t go out
preposition
3.
(often preceded by up) in or throughout the period before: he waited until six
4.
(used with a negative) earlier than; before: he won’t come until tomorrow

while loop