In a broader sense, subordination is a relation existing between two syntactic units, whereby the one unit is subordinate to the other and the latter is superordinate to the former. An adjective that modifies a noun is subordinate to the noun and the noun is superordinate to the adjective; a noun phrase (NP) that is the complement of a preposition is subordinate to the preposition and the preposition is superordinate to the NP; a prepositional phrase (PP) that modifies a verb phrase (VP) is subordinate to the VP and the VP is superordinate to the PP; etc. The subordinate unit is called the "dependent", and the superordinate unit the "head". Thus anytime two syntactic units are in a head-dependent relationship, subordination obtains. For example: