infinitive

Concise Oxford English Dictionary © 2008 Oxford University Press:
infinitive /ɪnˈfɪnɪtɪv/

▶noun the basic form of a verb, without an inflection binding it to a particular subject or tense (normally occurring in English with the word to, as in to see, to ask).

– derivatives
infinitival /-ˈtʌɪv(ə)l/ adjective,
infinitivally adverb.

– origin ME (as an adj.): from L. infinitivus, from infinitus (see infinite).