Formulas
- Transfinite number
- Transportation theory (mathematics)
- Transversal (combinatorics)
- Trefoil knot
- Triangulation (topology)
- Triviality (mathematics)
- Tropical geometry
- Truncation
- Tsen rank
- Tubular neighborhood
- Étale topos
- Weak convergence (Hilbert space)
- Weakly compact cardinal
- Web (differential geometry)
- Weight (representation theory)