Osmic

Part of speech: adjective

Definitions

1. Relating to osmosis, the movement of a solvent through a semi-permeable membrane from a weaker solution to a stronger one
2. Describing the passage of water or other solvent across a membrane, driven by differences in solute concentration on either side
3. Of or involving osmosis, the natural tendency of fluid to pass through a membrane toward a region of higher solute concentration

Etymology: Osmic has two unrelated parents, and the adjective "osmic" meaning "relating to osmosis" is not the one you might guess. Osmosis itself comes from the Greek "ōsmos," meaning "a push" or "impulse," but the adjective here is formed from the chemical element osmium, which was named for its smell. Osmium's name comes from the Greek "osmē," meaning "smell" or "odour," because its oxide gives off a pungent, distinctive odour when it is heated or exposed to air. The same Greek root also produced a second, separate "osmic." In that sense it is built directly from "osmē" plus the suffix "-ic," meaning "pertaining to smell," and it is a different word from the osmium-based form. Because the element and the physical process share only a sound, the adjective is easy to misread. The element's name stayed attached to the metal through its chemistry, while osmosis, the movement of a solvent across a membrane, earned its own vocabulary.