Paraformaldehyde

Part of speech: noun

Definitions

1. A solid polymer of formaldehyde that releases the gas slowly and is used to disinfect or preserve biological specimens
2. A white powdered polymer made from formaldehyde, often employed as a fixative for tissue samples and as a fumigant
3. A chemical compound formed by linking formaldehyde molecules, applied as a preservative, sterilizing agent and tissue fixative

Etymology: Paraformaldehyde is formaldehyde's solid cousin, and the prefix "para-" is the clue to its structure. In Greek, "para" meant "beside" or "beyond," and chemists borrowed it to mark a compound that is a polymer, a chain of formaldehyde units joined together. The word therefore names a multiple of the simple molecule rather than a different substance. Formaldehyde itself traces back to "aldehyde," a German coinage formed from "alcohol dehydrogenatum," which describes a molecule made by removing hydrogen from alcohol. English then added "formic" to the chain, since formaldehyde was first obtained from formic acid, and the name was built step by step from the chemical relationships between the compounds. Because the prefix carries the meaning, "paraformaldehyde" reads almost like a chemical sentence: a polymer of formaldehyde, with the "para-" signalling that repeated units are bonded together.