Transmissivity is a term commonly used in fields of optics, hydrology, and geology to describe the ability of a material to transmit light, heat, or liquid. However, there are many synonyms for the word which can be used to describe the same phenomenon. For instance, the term "transmittance" is often used in optics to denote the degree to which waves of light can pass through a given material. Similarly, in hydrology, one can use "infiltration" or "permeability" to indicate the degree to which water can penetrate the ground. Other synonyms of transmissivity include "conductivity," "porosity," and "ability to transmit" which appreciably convey the same meaning.