To protect, keep safe (from danger).
To give (someone) an assurance or guarantee (of something); also, with a double object: to guarantee (someone something).
To guarantee (something) to be (of a specified quality, value, etc.).
To guarantee as being true; (colloquially) to believe strongly.
That tree is going to fall, I’ll warrant.
To authorize; to give (someone) sanction or warrant (to do something).
I am warranted to search these premises fully.
To justify; to give grounds for.
Circumstances arose that warranted the use of lethal force.
A guarantee.