Infinitive mood

Related to Infinitive mood: infinitival
(Gram.) that form of the verb which merely names the action, and performs the office of a verbal noun. Some grammarians make two forms in English: (a) The simple form, as, speak, go, hear, before which to is commonly placed, as, to speak; to go; to hear. (b) The form of the imperfect participle, called the infinitive in -ing; as, going is as easy as standing.

See also: Infinitive

Webster's Revised Unabridged Dictionary, published 1913 by G. & C. Merriam Co.
References in classic literature ?
You are so impatient, sir, you would come at the infinitive mood before you can get to the imperative.
These results tally with the distribution of help in Present-Day English inasmuch as this verb is clearly reluctant to take a to-infinitive when the matrix verb is in the infinitive mood to avoid the use of two tos in a sequence (Kjellmer 1985, 159-160; also Lind 1983, 266).
Thus, while the unmarked form is more widespread when the verb make appears in the infinitive mood in order to avoid the likely repetition of two tos in a series, the other morphological forms do not present significant tendencies.