Origin of usable
Examples from the Web for unusable
New Jersey Transit has also been affected, with major stations and termini along the coast flooded and unusable.
The second part of this definition is, of course, unusable for beginners.The Teaching of Geometry|David Eugene Smith
And there it all lies now—unused and unusable for ever—of no earthly service to any one—just like the ruins left by a fire.The Master Builder|Henrik Ibsen
A month later a vision-phone circuit between Chicago and Los Angeles was unusable for ten minutes.The Machine That Saved The World|William Fitzgerald Jenkins