Quanta
photons
Discrete packages of light energy are called photons. Photons are also the quanta of all other electromagnetic radiation, not just light.
Light travels in the form of discrete paritcles called photons. These are measured by a unit called quantum.
The mean of a discrete probability distribution is also called the Expected Value.
A set which is made up only of isolated points is called a discrete set.
genes
It's called a Ray
A small discrete unit of energy is called a quantum of energy. The definition of quantum is a discrete quantity of energy proportional in magnitude to the frequency of the radiation that it represents.
Discrete Mathematics is mathematics that deals with discrete objects and operations, often using computable and/or iterative methods. It is usually opposed to continuous mathematics (e.g. classical calculus). Discreteness here refers to a property of subjects of discourse. Some collection of things is called discrete if these things are distinguishable and not continuously transformable into each other. An example would be the collection of natural numbers, but not the real numbers. In topology, a space is called discrete if every subset is open. In constructivism, a set is called discrete if equality of two elements is always decidable.
photon
The enrgy is always lost or gained in only the definite amount that is called as discrete or packet energy.
That would be a discrete variable; or, in your case, it would probably be called a discrete random variable.