Retinaldehyde

Part of speech: noun

Definitions

1. A chemical substance that functions as a precursor in the biosynthesis of vitamin A
2. A biochemical compound that serves as an intermediate in the formation of vitamin A in living organisms
3. An organic molecule involved in the metabolic pathway converting beta-carotene into vitamin A

Etymology: Retinaldehyde is a plain technical compound, built from two existing words joined together. "Retina" comes from Latin, where it referred to the membrane at the back of the eye, and in English it has long been the name for that light-sensitive layer. "Aldehyde" is a chemistry term formed from "alcohol" and "dehydrogenatum," reflecting that aldehydes are what alcohols become when hydrogen is removed from them. Joining the two gives a name that points to where the compound was first found and what it does. Retinaldehyde is the form of vitamin A used in the visual cycle, the process by which the retina's light-detecting cells recover after being exposed to light. The eye's chemistry is what the name records, while the aldehyde part tells chemists the molecule's functional group.