A verb utilized just into the infinitive or in the third-person. In the third person, the niche is either implied or a dummy.
adjective:
a verb used in combination with an indeterminate topic, generally, in English, because of the impersonal pronoun it; as, it rains; it snows; methinks (this indicates for me). Numerous verbs which are not strictly impersonal in many cases are utilized impersonally; because, it goes really with him.
How would you define impersonal verb?