Isopycnic

Part of speech: adjective

Definitions

1. Having or characterized by uniform density throughout a body of water, air, or other fluid ; a line on a chart joining points that share the same density
2. Describing a condition in which density remains constant across a region ; a contour drawn on a map linking locations of identical density
3. Of equal density at every point in a fluid mass ; an isopycnic line that traces places where a given density is found

Etymology: Isopycnic is built from two Ancient Greek words: "ísos", meaning "equal", and "puknós", meaning "thick" or "dense". Put together, the term describes something that has equal density throughout, which is why it is used in oceanography and physics for surfaces or lines where density stays constant. The first half is the same root that gives English "isosceles" (equal-legged) and "isotope" (same place, since isotopes occupy the same spot on the periodic table). The second half, "puknós", also gave English "pycnometer", an instrument for measuring density, and it sits behind words for dense or compact things in scientific Greek. The word is a technical coinage built from classical roots rather than a term that circulated in antiquity, so ancient Greeks would not have recognised it as a single word. Its meaning is fixed by its parts: "equal" plus "dense", applied to a surface where density does not vary.

Synonyms: isopycnal