1. (Science: zoology) a variety of dog, of remarkable ferocity, courage, and tenacity of grip; so named, probably, from being formerly employed in baiting bulls.
2. (Science: chemistry) a refractory material used as a furnace lining, obtained by calcining the cinder or slag from the puddling furnace of a rolling mill.
characteristic of, or like, a bulldog; stubborn; as, bulldog courage; bulldog tenacity.
(Science: zoology) bulldog bat, a bat of the genus Nyctinomus; so called from the shape of its face.