View source for Non-Finite (definition)

A non-finite clause is a clause where the verb/auxiliary does not contain the tense information of the event/action/state it describes.  For example, in an English sentence ''She wants [to go to school]'', the embedded clause in the brackets is non-finite in that the tense of the action described by the verb ''go'' is not expressed.

The subject of a non-finite clause can be omitted as in ''She wants [PRO to go to school]''; When it appears as a personal pronoun, it must inflect for accusative Case as in ''She wants [him go to school]'', as opposed to ''*She wants [he go to school]''.