The Collaborative International Dictionary
Infinitival
Infinitival \In*fin`i*ti"val\, a.
Pertaining to the infinite mood. ``Infinitival stems.''
--Fitzed. Hall.
Wiktionary
infinitival
a. Of, pertaining to, or formed from an infinitive
WordNet
infinitival
adj. relating to or formed with the infinitive; "infinitival clause"