bull·dog /ˈbʊlˌdɔg ||ˈbʌl-/
  牛頭犬;頑固的人
  Bull·dog n.
  1. Zool. A variety of dog, of remarkable ferocity, courage, and tenacity of grip; -- so named, probably, from being formerly employed in baiting bulls.
  2. Metal. A refractory material used as a furnace lining, obtained by calcining the cinder or slag from the puddling furnace of a rolling mill.
  Bull·dog, a. Characteristic of, or like, a bulldog; stubborn; as, bulldog courage; bulldog tenacity.
  Bulldog bat Zo'94l., a bat of the genus Nyctinomus; -- so called from the shape of its face.
  ◄ ►
  bulldog
       adj : stubbornly unyielding; "dogged persistence"; "dour
             determination"; "the most vocal and pertinacious of all
             the critics"; "a mind not gifted to discover truth but
             tenacious to hold it"- T.S.Eliot; "men tenacious of
             opinion" [syn: dogged, dour, pertinacious, tenacious,
              unyielding]
       n : a sturdy thickset short-haired breed with a large head and
           strong undershot lower jaw; developed originally in
           England for bull baiting [syn: English bulldog]
       v 1: attack viciously and ferociously
       2: throw a steer by seizing the horns and twisting the neck, as
          in a rodeo
       [also: bulldogging]