Exosmosis

Part of speech: noun

Definitions

1. The movement of a liquid or gas outward through a selectively permeable membrane, moving from the more concentrated side to the more dilute side
2. Passage of solvent out of a cell or compartment across a membrane, driven by differences in concentration on either side of the barrier
3. The process by which fluid diffuses outward through a membrane that lets some substances pass while blocking others, as in biological cells

Etymology: Exosmosis is the flow of fluid outward through a membrane, the reverse-direction partner of its better-known sibling "endosmosis", which runs inward. The "exo-" comes from Ancient Greek "ἔξω" ("éxō"), meaning "outside" or "outward", and it descends from the same root as the Greek preposition "ek", meaning "out of". Attached to "osmosis", it names the outward movement, so the pair of words describes two directions of one process. "Osmosis" itself was coined in the nineteenth century from Greek "ōsmos", meaning "a push" or "impulse", a reference to the force with which fluid pushes through a membrane. Scientists then built "exosmosis" and "endosmosis" from it, giving English a matched pair of terms for flow in each direction.

Antonyms: endosmosis