formaldehyde

American  

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

noun

Chemistry.

1. a colorless, toxic, potentially carcinogenic, water-soluble gas, CH 2 O, 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.

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formaldehyde British  

/ fɔːˈmældɪˌhaɪd /

noun

1. Systematic name: methanal.  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: HCHO

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formaldehyde Scientific  

/ fôr-măl′də-hīd′ /

1. 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: CH ₂ O.

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Etymology

Origin of formaldehyde

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

Compare meaning

How does formaldehyde compare to similar and commonly confused words? Explore the most common comparisons:

• paraformaldehyde vs. formaldehyde

Explanation

No, formaldehyde is not a formal hiding place. Formaldehyde is a strong-smelling colorless gas. Depending on what other elements are combined with it, formaldehyde is used for embalming, manufacturing, and all kinds of other things. Formaldehyde is really good at helping things stick together, which is why it's often used in making things like particleboard and some insulation materials found in buildings. It’s also found in some glues and paints. Besides helping things stick, formaldehyde is famous in science labs for preserving biological specimens, like animals and plants, so that they can be studied without decaying.

Example Sentences

Preserved in formaldehyde and paraffin wax, they come from patients treated at the UK's national bowel hospital, St Mark's, in northwest London.

From Barron's • Feb. 4, 2026

In 2021, researchers at the University of California, Berkeley found that acute exposure to the chemical formaldehyde led to a 78% increase in the risk of developing ALS and a 71% increase in brain cancer.

From The Wall Street Journal • Dec. 22, 2025

In addition to smoke and soot, the space agency detected large plumes of harmful gases emanating from the wildfires, including lung-irritating nitrogen dioxide and cancer-causing formaldehyde.

From Los Angeles Times • Jan. 16, 2025

Some VOCs, such as dioxins, benzene, formaldehyde and PAHs, can be toxic to humans.

From Salon • Jan. 8, 2025

I could smell her perfume even over the formaldehyde.

From "October Sky" by Homer Hickam

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