Just as we find with breath and breathe or sale and sell, it is very easy for people to misunderstand how to use the words lose, loose, and loss. They are all pronounced differently and hold very different meanings.
Lose is a verb that has two main definitions. First, to lose something could mean to fail to keep it or maintain it in your possession. For example, you could say that it is easy to lose all your money while gambling in Las Vegas. This can also be used in an abstract sense to refer to the passing of a loved one (“she lost her husband in the war”) or losing sight of someone while in pursuit.
Second, to lose could refer to not winning a game, match, or battle. For instance, you could predict that the Calgary Flames are going to lose the NHL season opener against the Vancouver Canucks.
Loose is an adjective and not a verb. It describes an object of some kind. You could say that a cable connection is loose and that’s why you television isn’t working. You could also say that a criminal is on the loose and the local authorities are trying to catch him. In general, the adjective “loose” would refer to something that is not compact in nature (“loose rock”), not being possessed in a sport (“loose ball”), or not being closely constricted (“loose clothing”).
Be mindful of the difference between loose and loosen, since the latter is a verb. You cannot tell someone to loose something. They can lose (possession of) it or they can loosen it (like a screw).
Loss is a noun with multiple uses. Going back to the hockey example, you could say that Calgary blames their loss to the Canucks on poor goaltending. A loss can also refer to a gradual decline, like weight loss. Selling something “at a loss” means that the sale price is lower than the purchase price. You can also describe the loss of credibility that someone would have if they were caught cheating on a university exam.
Whether or not you are a professional writer, it is important to have good grammar. I’m assuming that you want to be respected by your peers and one of the fastest ways to lose their respect is for you to have a loose grasp on proper grammar. Don’t suffer that loss. Keep good grammar in mind.