Formothioaldehyde

Part of speech: noun

Definitions

1. The sulfur analogue of formaldehyde, a highly reactive chemical compound with the formula CH2S
2. A reactive sulfur-containing compound in which sulfur takes the place of oxygen in the formaldehyde structure
3. A chemical compound, the thio version of formaldehyde, that is unstable and reacts readily with other substances

Etymology: Formothioaldehyde is a chemistry coinage rather than a word with an ancient or folk history, so its story is one of systematic naming. It is built from "formo-", a clipped form of "formaldehyde", combined with "thio-", the chemical prefix meaning "containing sulfur" (from Greek "theion", "sulfur"), and "aldehyde", a term coined in the 1830s by Justus von Liebig as a shortening of "alcohol dehydrogenatum", reflecting that aldehydes are alcohols with hydrogen removed. The name thus describes the molecule's structure in layers: a formaldehyde-type core in which one oxygen atom is replaced by sulfur. Chemists devised such names in the late 19th and 20th centuries, when the growing number of compounds demanded a systematic vocabulary. The word is essentially a label assembled from parts, and its meaning lies in those parts rather than in any older usage.