Other answers have seemed to overlook the fact that you are requesting a term from linguistics. I don't think *axiomatic* is what you're after.

I believe the term you are looking for is *categorematic*.

***Categorematic*** words are "words that designate self-sufficient entities (i.e. nouns or adjectives)" ([here][1]) or words "that are capable of being employed alone as a term" ([here][2]).

Merriam-Webster defines ***categorematic*** as "capable of standing alone as the subject or predicate of a logical proposition :  expressing a complete substantive meaning" ([here][3]).

***Syncategorematic*** words are words "that do not stand by themselves... (i.e. prepositions, logical connectives, etc.)" ([here][1]).

That fact that these definitions explicitly mention "standing by themselves", "standing alone", and "being employed alone" suggests that they fit what you're looking for.


  [1]: https://en.wikipedia.org/wiki/Syncategorematic_term
  [2]: https://en.wiktionary.org/wiki/categorematic
  [3]: http://www.merriam-webster.com/dictionary/categorematic