- a number representing an estimate of the potentially debilitating effect of temperature and relative humidity on humans and animals, especially livestock: computed essentially as a combination of dry-bulb temperature and wet-bulb temperature but formulaically specific to a given species, as heat-stress tolerances vary significantly from one species to another. Abbreviations: THI, T.H.I.
- an index of the effect on human comfort of temperature and humidity levels, 65 being the highest comfortable level
