Synonyms of the word 
NON-NEGOTIABLE → INALIENABLE - UNALIENABLE
non-negotiable
- adj. Not negotiable; not subject to negotiation.
inalienable
- adj. Incapable of being alienated, surrendered, or transferred to another; not alienable.
- adj. (grammar) Of or pertaining to a noun belonging to a special class in which the possessive construction…
unalienable
- adj. Not alienable.
If you are interested in words, visit the following sites :
- wiktionary.org/non-negotiable For complete definition of a word
- 1word.ws/nonnegotiable to play with words, suffixs, prefixs, etc.