Opacifier

Part of speech: noun

Definitions

1. A chemical that diminishes the clarity of a mixture by blocking or scattering light rays
2. A material added to liquids or solids to lessen their transparency by preventing light from passing through clearly
3. An agent used to make a mixture less see-through by dispersing or absorbing light rays

Etymology: The most useful way to read "opacifier" is as a piece of plain English machinery: "opacify" (to make something opaque) with the agent suffix "-er" added, meaning the thing that does the opacifying. The suffix itself has a long pedigree. It passed from Latin "-arius", through Old French "-ier", into Middle English as "-er", and was already in use in Old English as "-ere", so it has been attached to native and borrowed verbs for well over a thousand years. "Opacify" is the older building block, formed from "opaque" with the Latin-derived verb ending "-ify", meaning "to make". "Opaque" itself came into English from Latin "opacus", "shaded", so the whole chain runs from a Latin word for shade to a modern word for a substance that blocks light. The word is a straightforward compound of established parts rather than a coinage with a famous inventor, so its interest lies mainly in how neatly the pieces fit together.