Lose vs loose - what's the difference?

Lose (verb) - to misplace something, or to not win. One o. Rhymes with choose.
"I always lose my keys."
"We don't want to lose the match."
"She's afraid of losing her job."

Loose (adjective) - not tight; free; not fastened. Two os. Rhymes with moose.
"These jeans are too loose."
"The dog got loose and ran off."
"A loose tooth."

Writers often write loose when they mean lose:
"I don't want to loose this opportunity." ✗ → "I don't want to lose this opportunity." ✓

Loose can also be a verb (less common): to release or set free:
"They loosed the horses into the field."
But in modern English, let loose or release is more natural.

Lose lost an o (it only has one). If the word has two os, it's the adjective meaning "not tight."