- pencil of collinear planes
- pencil of intersecting planes
- pencil of lines
- pencil of lines in a Lobachevskian plane
- pencil of parallel planes
- pencil of parallel straight lines
- pencil of planes
- pencil of quadratic forms
- pencil of straight lines
- p-endomorphism
- pendulum
- Penrose process
- pentagonal dodecahedron
- pentagonal number
- pentagonal number
- pentagon-type lattice
- pentahedron
- Pepin test
- percent
- percent
- percentage
- percentage error
- percentage problem
- percentile deviation
- perceptron