z-Axis
The axis in 3-D Cartesian Coordinates which is usually oriented vertically. Cylindrical Coordinatesare defined such that the 
-axis is the axis about which the azimuthal coordinate 
is measured.
- Perspective Triangles
- Perspectivity
- Pesin Theory
- Petersen Graphs
- Petersen-Shoute Theorem
- Peters Projection
- Peter-Weyl Theorem
- Petrie Polygon
- Petrov Notation
- Pfaffian Form
- p-Good Path
- p-Group
- Phase
- Phase Space
- Phase Transition
- Phasor
- Phi Curve
- Phi Number System
- Phragmén-Lindêlöf Theorem
- Phyllotaxis
- Pi
- Piano Mover's Problem
- Picard's Existence Theorem
- Picard's Little Theorem
- Picard's Theorem