- notumThe back; the dorsal side of the thorax in insects or nudibranches.
- notaeumThe back (upper surface) of a bird.
- notariumA bone formed of fused vertebrae behind the shoulder of many species of birds and pterosaurs.
- noto-south, southern
- notothyriumA triangular opening at the back edge of a brachiopod's brachial valve through which the pedicle may partially protrude.