split infinitive
English grammatical construction in which a word or phrase (usually adverb or adverbial phrase) comes between the to and the bare infinitive of the to form of the infinitive verb; e.g. “to boldly go”; “to more than double”
en-GB/ˈsplɪt ɪnˈfɪnətɪv/
en-US/split ɪnˈfɪnɪtɪv/