A split infinitive or cleft infinitive is an English-language grammatical construction in which a wor or phrase, usually an adverb or other adverbial, comes between the marker to and the bare infinitive (uninflected) form of a verb. A famous split infinitive occurs in the opening sequence of the Star Trek television series: to boldly go where no man has gone before. Here, the adverb "boldly" splits the full infinitive "to go." More rarely, the term compound split infinitive is used to describe situations in which the infinitive is split by more than one word: The population is expected to more than double in the next ten years.