Astrophysics

Part of speech: noun

Pronunciation: /ˌæs.tɹoʊˈfɪz.ɪks/

Definitions

1. The field dedicated to exploring the physical characteristics and behaviors of celestial entities in the cosmos
2. An area of science concerned with the fundamental principles that explain the interactions and features of objects in space
3. A branch of science that investigates the properties and dynamics of celestial bodies and phenomena, applying physical laws to their behavior

Etymology: Astrophysics is a compound built from two Greek-derived halves, and the older one is the more surprising. "Astro-" comes from ancient Greek "astēr", meaning star, while "physics" traces back to "phusis", a word for nature or the natural growth of things, which in turn grew out of the Greek verb "phuō", to produce or bring forth. So the whole word literally means something like "the nature of the stars," and "physics" once meant the study of nature in general, long before it narrowed to the laws of matter and energy. The "physics" half passed through Latin, where "physicus" meant natural philosophy, and then through Middle English before settling into its modern form. "Astro-" stayed attached to stars as a prefix in many older Greek-based words, such as "astronomy," which predates this compound by centuries. The combination is a modern coinage. It was formed by joining the two established elements, so it is a straightforward technical term rather than a word with an ancient pedigree of its own.