What is the term for a connective word used to join sentences, clauses, phrases, or words?

The term for a connective word used to join sentences, clauses, phrases, or words is a conjunction.

There are three main types of conjunctions:

* Coordinating conjunctions: These join words, phrases, or clauses of equal grammatical rank. Examples include "and", "but", "or", "nor", "for", "yet", and "so".

* Subordinating conjunctions: These join a dependent clause to an independent clause. Examples include "because", "although", "since", "while", "if", "when", "where", and "unless".

* Correlative conjunctions: These come in pairs and join words, phrases, or clauses that are grammatically parallel. Examples include "both...and", "either...or", "neither...nor", "not only...but also", and "whether...or".