guarantee

verb1 of 2

to make a formal promise that something will happen or be done.

• “A brand name does not constitute a guarantee of quality.”Tatoeba
• “Pain is one of the few things guaranteed in life.”Tatoeba

Sentences from Tatoeba show real usage. A word can have several meanings, so a sentence may use another one.

noun2 of 2

Anything that assures a certain outcome.