constituent

noun

1.
an artifact that is one of the individual parts of which a composite entity is made up; especially a part that can be separated from or attached to a system
Derived from:
constitute
2.
a member of a constituency; a citizen who is represented in a government by officials for whom he or she votes
3.
something determined in relation to something that includes it
4.
(grammar) a word or phrase or clause forming part of a larger grammatical construction