Coordinators in English grammar are function words that join or link two or more words, phrases, and clauses. Function words perform definite grammatical functions but lack definite lexical meaning.
Coordinator is a grammatical function.
The grammatical form that can function as the coordinator in English grammar is the coordinating conjunction.
The seven coordinating conjunctions in English are and, but, or, nor, so, yet, and for.
Brinton, Laurel J. & Donna M. Brinton. 2010. The linguistic structure of Modern English, 2nd edn. Amsterdam: John Benjamins Publishing Company.
Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.