Middle English loos 'free from bonds,' from Old Norse lauss, of Germanic origin; related to Dutch and German los
The adjective loose, meaning ‘not tight,’ should not be confused with the verb loose, which means ‘let go’: they loosed the reins and let the horse gallop. This verb in turn should not be confused with the verb lose, which means ‘be deprived of, fail to keep’: I will lose my keys if I don’t mend the hole in my pocket.
Do not confuse loose with lose. Loose means 'not firmly fixed or fastened' (the handle was loose) or 'unfasten or set free something' whereas lose means 'no longer have something' (you could easily win or lose $3,000).