rarefied

Rarefied is an adjective that describes something that is thin, sparse, or dilute. It can also refer to something that is elevated or lofty in a metaphorical sense. The term originates from the Latin word "rarus," meaning rare or thin, and the French word "rarefier," meaning to make thin or rare. In a scientific context, rarefied refers to a gas that has been expanded to a low density, often used in the study of gas dynamics and aerodynamics. For example, a rarefied gas may have a low pressure and a high mean free path, where the distance between collisions is large compared to the size of the molecules. In a more general sense, something that is rarefied may be described as being rare, unusual, or not common. For instance, a rarefied book collection might contain only a few valuable editions, making it a unique and sought-after resource. The term can also be used to describe a state of mind or atmosphere that is elevated or detached from everyday concerns, such as a rarefied discussion among intellectuals.