usable
Word family
Synonym discussion
Sense: adjective/1
Usable is the broadest of these four: it simply means something can be used, whether because it works, is free, or is accessible. Functional narrows the focus to whether the thing operates properly — a phone with a cracked screen may be usable but not fully functional if the touch input is affected. Serviceable is more formal and implies the item works adequately for its purpose despite visible wear or imperfection, like a ten-year-old car that still gets you to work every morning. Available adds the dimension of access: something may be perfectly functional yet not usable because it is locked away or already in someone else's hands. For everyday situations, choose usable for general situations, functional when checking operation, and available when access is the barrier.
Common collocations
Etymology
Usable comes from the Old French word 'usable', meaning 'that can be used', which developed from the verb 'user' (to use). The French verb traces back to the Latin 'usus', the past participle of 'uti' (to use, to make use of). The word entered English in the late 1300s and has been spelled 'usable' consistently since the 1700s, though the variant 'useable' appears occasionally in British writing.