In linguistics, subordination is a principle of the hierarchical organization of linguistic units. While the principle is applicable in semantics, morphology, and phonology, most work in linguistics employs the term "subordination" in the context of syntax, and that is the context in which it is considered here. The syntactic units of sentences are often either subordinate or coordinate to each other. Hence an understanding of subordination is promoted by an understanding of coordination, and vice versa.

In linguistics, coordination is a complex syntactic structure that links together two or more elements; these elements are called conjuncts or conjoins. The presence of coordination is often signaled by the appearance of a coordinator, e.g. and, or, but. The totality of coordinator(s) and conjuncts forming an instance of coordination is called a coordinate structure. The unique properties of coordinate structures have motivated theoretical syntax to draw a broad distinction between coordination and subordination. It is also one of the many constituency tests in linguistics. Coordination is one of the most studied fields in theoretical syntax, but despite decades of intensive examination, theoretical accounts differ significantly and there is no consensus on the best analysis.