What term describes a thermodynamic process with no heat transfer?

What term describes a thermodynamic process with no heat transfer? The answer is adiabatic. In an adiabatic process, no heat enters or leaves the system, so Q = 0. Energy can still cross the system boundary as work or, in an open system, through mass flow. “No heat transfer” does not mean that the system’s temperature remains constant.

Adiabatic behavior can result from excellent insulation or from a process occurring so quickly that there is not enough time for significant heat exchange. Rapid compression and expansion of gases are often approximated as adiabatic. Sound waves traveling through air are also commonly modeled as adiabatic because heat conduction is negligible over the short timescale.

The term comes from Greek roots meaning “not passable,” referring to heat not passing through the boundary. A reversible adiabatic process is also isentropic, meaning its entropy remains constant, but an irreversible adiabatic process can produce entropy. This distinction is frequently overlooked. Isochoric means constant volume, isobaric means constant pressure, and isothermal means constant temperature.