What does "dogtooth" mean?

Dogtooth: (Arch.) An ornament common in Gothic architecture, consisting of pointed projections resembling teeth; -- also called tooth ornament. Dogtooth spar (Min.), a variety of calcite, in acute crystals, resembling the tooth of a dog. See Calcite. -- Dogtooth violet (Bot.), a small, bulbous herb of the Lily family (genus Erythronium). It has two shining flat leaves and commonly one large flower. [Written also dog's-tooth violet.]