In X-bar theory and other grammatical theories that incorporate it, an inflectional phrase or inflection phrase (IP or InflP) is a functional phrase that has inflectional properties (such as tense and agreement). An inflectional phrase is essentially the same as a sentence, but reflects an analysis whereby a sentence can be treated as having a head, complement and specifier, like other kinds of phrases. Inflectional morphology, therefore, occurs after sentence construction is complete.