Noun

1. an infinitive with one or more modifiers inserted between the to and the verb
   • "To boldly go where no one has gone before."
   • "Did you ever have to finally decide?" ("Did You Ever Have to Make Up Your Mind?" by the Lovin' Spoonful, 1965)

Usage notes

• The use of split infinitives has long been considered undesirable in formal speech or writing, because of models of Latin grammar where the infinitive is a single word and so cannot be split. However, most grammarians for at least the past hundred years have seen little wrong with the concept, and it remains a common construction in English.