Isohaline

Part of speech: adjective, noun

Definitions

1. A situation where the salinity of a body of water is consistently the same regardless of depth or location
2. A phenomenon in aquatic environments where salinity levels remain homogeneous regardless of depth or position in the water column
3. Describing a water body where salt concentration stays constant at all depths and locations

Etymology: "Isohaline" is a plain technical coinage, built from two parts that are each easy to pull apart. The first, "iso-", comes from Greek "isos", meaning "equal" or "same", and appears in many scientific terms where something is uniform or constant. The second, "haline", comes from Greek "hals", "salt", through the adjective-forming suffix "-ine", as in "saline". Put together, the word describes a body of water or a line on a map where salinity is the same throughout. The word belongs to the vocabulary of oceanography, where scientists plot salinity across a sea or estuary. Its usefulness lies in the way it lets researchers name a whole class of boundaries and zones at once rather than describing each one afresh. The noun form refers to such a line, usually drawn on a chart, connecting points of equal salt concentration.