- a colorless, irritating, fuming, water-soluble liquid, CH2O2, originally obtained from ants and now manufactured synthetically, used in dyeing and tanning and in medicine chiefly as a counterirritant and astringent.
- a colourless corrosive liquid carboxylic acid found in some insects, esp ants, and many plants: used in dyeing textiles and the manufacture of insecticides and refrigerants. Formula: HCOOH
