1. Not capable of being used
   "The concept of the unserviceable library is more familiar to library users than to librarians";
   - unusable, unuseable
    
2. Not ready for service
   "unserviceable equipment may be replaced"

See also: broken-down, burned-out, burnt-out, cactus [Austral, NZ, informal], inoperable, nonfunctional, unrepaired, useless

Antonym: serviceable