usable

Something is usable when it can be used for its intended purpose without much problem.

When talking about things we use every day, like furniture or electronic devices, we often wonder if something is usable. For example, if you buy a second-hand bike, you might check to see if the brakes are working properly and if the chain isn't rusty - in other words, if it's usable for riding. If you move into a new apartment, you'll probably want to know if the oven works before using it.