The spelling is the whole problem. English usually doubles a letter to lengthen a vowel, so "loose" reading as a long sound and "lose" as a short one is consistent — but it runs against the instinct that more letters means more emphasis. People write "loose" when they mean "lose" far more often than the reverse, probably because the doubled "o" looks more deliberate.
A verb. To misplace something, to fail to win, or to be deprived of something.
An adjective meaning not tight, not fastened, or not precise. Occasionally a verb meaning to release.
Quick way to remember
Count the letters against the meaning. "Lose" has lost an "o" — it is the word about losing things. If you can replace the word with "not tight" or "slack," you want "loose."