[adj] convenient for use or disposal; "the house is available after July 1"; "2000 square feet of usable office space"
[adj] fit or ready for use or service; "the toaster was still functional even after being dropped"; "the lawnmower is a bit rusty but still usable"; "an operational aircraft"; "the dishwasher is now in working order"
[adj] able to be put to use; "usable byproducts"