[ fawr-mal-duh-hahyd, fer- ]
/ fɔrˈmæl dəˌhaɪd, fər- /

noun Chemistry.

a colorless, toxic, potentially carcinogenic, water-soluble gas, CH2O, having a suffocating odor, usually derived from methyl alcohol by oxidation: used chiefly in aqueous solution, as a disinfectant and preservative, and in the manufacture of various resins and plastics.

Nearby words

  1. formal equivalence,
  2. formal language,
  3. formal logic,
  4. formal mode,
  5. formal system,
  6. formalin,
  7. formalin pigment,
  8. formalise,
  9. formalism,
  10. formality

Compare formalin.

Origin of formaldehyde

1870–75; form(ic) + aldehyde; modeled on German Formaldehyd

Also called methanal. Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for formaldehyde

British Dictionary definitions for formaldehyde


/ (fɔːˈmældɪˌhaɪd) /


a colourless poisonous irritating gas with a pungent characteristic odour, made by the oxidation of methanol and used as formalin and in the manufacture of synthetic resins. Formula: HCHOSystematic name: methanal

Word Origin for formaldehyde

C19: form (ic) + aldehyde; on the model of German Formaldehyd

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for formaldehyde



pungent gas formed by oxidation of methyl alcohol, 1869, a contraction of formic aldehyde; see formic + aldehyde. Discovered in 1863 by German chemist August Wilhelm von Hofmann (1818-1892).

Online Etymology Dictionary, © 2010 Douglas Harper

Medicine definitions for formaldehyde


[ fôr-măldə-hīd′ ]


A colorless, gaseous compound that is the simplest aldehyde, used for manufacturing melamine and phenolic resins, fertilizers, dyes, and embalming fluids and in aqueous solution as a preservative and disinfectant.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Science definitions for formaldehyde


[ fôr-măldə-hīd′ ]

A colorless gas having a sharp, suffocating odor. It is used in making plastics and, when dissolved in a solution of water and methanol, to preserve biological specimens. Chemical formula: CH2O.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.