| Abbreviation | Definition |
|---|---|
| HLT | Hypotenuse Leg Theorem |
| HMM | Hidden Markov Model |
| HMMT | Harvard MIT Mathematics Tournament |
| HMMT | Harvard–MIT Mathematics Tournament |
| HMR | Hybrid Mechanical Rule |
| HN | Hypothetically Necessary |
| HNN | Higman Neumann Neumann |
| HO | Higher Order |
| HOA | Hands On Algebra |
| HOC | Higher Order Crossing |
| HP | Harmonic Progression |
| HPD | Hermitian Positive Definite |
| HPN | Highest Possible Number |
| HQE | Hemi-Quantal Equation |
| HR | hazard ratio |
| HR | Hyper Real |
| HR(s) | hazard ratio(s) |
| HRB | Horwitz, Reps, and Binkley algorithm |
| HRF | Hyper Real Field |
| HRM | High Ratio Multiplier |