ADJECTIVE (1)

1. beyond the legal power or authority of a person or official or body etc;
- Example: "an ultra vires contract"


ADVERB (1)

1. beyond the scope or in excess of legal power or authority;

The Collaborative International Dictionary of English v.0.48:

Ultra vires \Ul`tra vi"res\, [Law Latin, from L. prep. ultra
   beyond + vires, pl. of. vis strength.]
   Beyond power; transcending authority; -- a phrase used
   frequently in relation to acts or enactments by corporations
   in excess of their chartered or statutory rights.
   [1913 Webster]

WordNet (r) 3.0 (2006):

ultra vires
    adv 1: beyond the scope or in excess of legal power or authority
    adj 1: beyond the legal power or authority of a person or
           official or body etc; "an ultra vires contract" [ant:
           intra vires]