What does isochoric mean?
Isochoric is a technical adjective meaning that volume or capacity remains the same. Its most important modern use is in thermodynamics, where an isochoric process occurs at constant volume: heat may be added to a substance, causing its temperature and pressure to change without any change in volume. The term also has the broader sense of having equal volume or being equal in capacity. It belongs to a family of scientific words built on Greek iso-, meaning “equal,” combined with different terms identifying the quantity that remains unchanged. For instance, isobaric processes maintain constant pressure, while isothermal processes maintain constant temperature. Although isochoric is not likely to occur in ordinary conversation, it is useful in scientific descriptions because it identifies precisely which physical variable is being held constant. In less specialized writing, constant-volume is usually clearer and more accessible.
adjectiveHaving equal volume or capacity; specifically, describing a thermodynamic process in which volume remains constant.
- Having equal volume or capacity.
- Relating to or occurring at constant volume, especially in thermodynamics.
"The gas underwent an isochoric heating, so its pressure rose while its volume stayed unchanged."
"The laboratory compared the temperature changes produced by isochoric and isobaric processes."
"Two isochoric containers may hold different amounts of matter while enclosing the same volume."
Isochoric means the volume stays put—even when the pressure and temperature are busy changing.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does isochoric come from?
Isochoric was formed from Greek iso-, meaning “equal,” and a Greek element associated with space or place, expressing the idea of equal volume or capacity. Its scientific sense developed alongside the study of gases and thermodynamic processes. Modern compounds such as isobaric, isothermal, and isochronous share the same Greek prefix for equality but specialize different physical quantities or rates.
Related word forms
How isochoric is actually used
This is a specialized term, used chiefly in physics, chemistry, engineering, and thermodynamics. It is more technical than the plain-language expression constant-volume.
Easily confused with isochoric
Isometric refers to equality of dimensions or lengths, whereas isochoric refers to equality of volume or capacity.