1. Suitable and good enough to employ or to put into service; serviceable: The hedge trimmer was still usable although it hadn't been sharpened in the past year.
2. Operable; functional: Clive's car was usable because it had been repaired at the garage the other day.
3. Practical and convenient for utilizing: The classroom was large enough to be usable by all the students with enough desks for everyone.