(mathematics) That portion of a surface that remains after an open disk is removed from it.
Perforation Sentence Examples
A large number of mammals possess a perforation, or foramen, on the inner side of the lower end of the humerus, and also a projection on the shaft of the femur known as the third trochanter.
- Amphicoelous; parietals separate; clavicles dilated and with a perforation near the ventral end.
Here the merit of nickel steel is not so much that it resists perforation, as that it does not crack even when deeply penetrated by a projectile.
the gill-slits may be stated briefly as follows: - (a) the presence of two kinds of branchial bars in all species and also of small cross bars (synapticula) in many species; (s) numerous gill slits, from forty to more 1 - _ than a hundred pairs; (y) the addition of new gill-slits by fresh perforation at the posterior end of the pharynx throughout life.
The vertebrae of the neck unite by nearly flat surfaces, the humerus has lost the foramen, or perforation, at the lower end, and the third trochanter to the femur may also be wanting.