Synonyms of the word 
UNUSABLE → UNSERVICEABLE - USELESS
unusable
- adj. Not usable.
unserviceable
- adj. unusable.
- adj. not working (machinery, etc).
- adj. impractical.
useless
- adj. Without use or possibility to be used.
- adj. Unhelpful, not useful; pointless (of an action).
- adj. (pejorative, of a person) good-for-nothing; not dependable.
- adj. (colloquial, of a person) unable to do well at a particular task or thing. Useless is mildly insulting.
If you are interested in words, visit the following sites :
- wiktionary.org/unusable For complete definition of a word
- 1word.ws/unusable to play with words, suffixs, prefixs, etc.