unless

conj

1. Except on a specified condition; if not.

   “I’m leaving unless I get a pay rise.”

   “You can't go out unless it stops raining.”

   “Unless part of the staff, you are not allowed beyond this point.”

   “Secondly, When a body is once in motion it will continue to move forever, unless something stops it. When a ball is struck on the surface of the earth, the friction of the earth and the resistance of the air soon stop its motion.”

   “Unless someone like you...cares a whole awful lot...nothing is going to get better...It's not.”

2. If not; used with counterfactual conditionals.

   “Who would know of Alexander or Caesar, or would respect the Stoics or the Peripatetics, unless they had been distinguished by the memorials of writers?”

   “And Joab said, As God liveth, unless thou hadst spoken, surely then in the morning the people had gone up every one from following his brother.”

   “Unless He were omnipotent, we could not be sure of His ability to bless us.”

3. Except if; used with hypothetical conditionals.

   “Q. If Lieutenant P. had given the word "Fire," would you have fired, and at what?—A. I should not have known, unless he had told me what to fire at.”

   “Lie down and finish out the night, since you are here; but, for heaven's sake! don't repeat that horrid noise: nothing could excuse it, unless you were having your throat cut!”

   “Suppose Breugel had done the whole painting with no legs. Then, titled as it is, it would be mystifying, unless someone were to say: the boy has fallen in the waters and they have closed over him, calm is restored, life goes on (as in The Israelites Crossing the Red Sea).”