What is the term that refers to a measure of disorder or randomness in a system?

The term that refers to a measure of disorder or randomness in a system is entropy. In thermodynamics, entropy quantifies the amount of uncertainty or the number of possible arrangements of particles in a system. A higher entropy value indicates a greater degree of disorder, whereas lower entropy signifies a more ordered state.

Entropy is a fundamental concept in the second law of thermodynamics, which states that in any energy transfer or transformation, the total entropy of an isolated system can never decrease over time. This principle allows us to understand processes such as why heat flows from hot to cold objects and why certain reactions occur spontaneously.

Considering the other choices, enthalpy relates to the total heat content of a system, free energy is a measure that accounts for enthalpy and entropy to determine the spontaneity of a process, and kinetic energy pertains to the energy of motion, rather than disorder. Thus, when seeking a term that specifically describes disorder or randomness, entropy is the accurate choice.