(geometry) A torus is a surface or solid formed by rotating a closed curve, such as a circle, about a line in the same plane, and can also refer to a topological space formed by the product of two circles or a ring-shaped chamber used in physical research.

(architecture) A large convex molding, typically semicircular in cross section, which commonly projects at the base of a column and above the plinth.

(anatomy) A rounded ridge of bone or muscle, especially one on the occipital bone.

(botany) The end of the peduncle or flower stalk to which the floral parts (or in the Asteraceae, the florets of a flower head) are attached.

(botany) The thickening of a membrane closing a wood-cell pit (as of gymnosperm tracheids) having the secondary cell wall arched over the pit cavity.