- triangular norms
- triangular numbers
- triangular numbers
- triangular operator algebra
- triangular pyramid
- triangulated graph
- triangulated space
- triangulation
- triangulation
- triangulation
- triangulation
- triangulation chain
- triangulation network
- triangulation point
- trichotomy for cardinals
- trichotomy of an ordered set
- trichotomy of natural numbers
- Tricomi equation
- Tricomi problem
- tricomplex
- tricotyledon theory of system design
- tri-dimensional scatter diagram
- Triebel-Liaorkin space
- trigonometric accuracy
- trigonometric circle