The Collaborative International Dictionary of English v.0.48:

Impersonal \Im*per"son*al\, a. [L. impersonalis; pref. im- not +
   personalis personal: cf. F. impersonnel. See Personal.]
   Not personal; not representing a person; not having
   personality.
   [1913 Webster]

         An almighty but impersonal power, called Fate. --Sir J.
                                                  Stephen.
   [1913 Webster]

   Impersonal verb (Gram.), a verb used with an indeterminate
      subject, commonly, in English, with the impersonal pronoun
      it; as, it rains; it snows; methinks (it seems to me).
      Many verbs which are not strictly impersonal are often
      used impersonally; as, it goes well with him.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Impersonal \Im*per"son*al\, n.
   That which wants personality; specifically (Gram.), an
   impersonal verb.
   [1913 Webster]

WordNet (r) 3.0 (2006):

impersonal
    adj 1: not relating to or responsive to individual persons; "an
           impersonal corporation"; "an impersonal remark" [ant:
           personal]
    2: having no personal preference; "impersonal criticism"; "a
       neutral observer" [syn: impersonal, neutral]