- : A pungent gas, with the chemical formula HCHO, used as an antiseptic, disinfectant, and especially today as a fixative for histology (the study of tissues under the microscope). Formalin is a 37% aqueous (water) solution of formaldehyde.
* * *A pungent gas, HCHO; used as an antiseptic, disinfectant, and histologic fixative. SYN: formic aldehyde, methyl aldehyde. [form(ic) + aldehyde]- active f. 1. a hydroxymethyl derivative of tetrahydrofolate or thiamin pyrophosphate; 2. N5,N10-methylenetetrahydrofolate.
* * *form·al·de·hyde fȯr-'mal-də-.hīd, fər- n a colorless pungent irritating gas CH2O used chiefly as a disinfectant and preservative and in chemical synthesis
* * *n.the aldehyde derivative of formic acid, formerly used as a vapour to sterilize and disinfect rooms and such items as mattresses and blankets. The toxic vapour is produced by boiling formalin in an open container or using it in a sealed autoclave.
* * *for·mal·de·hyde (for-malґdə-hīd) a gas formerly used as a strong disinfectant; an aqueous solution called formaldehyde solution (see under solution) is used as a disinfectant and as a preservative and fixative for pathologic specimens. The gas is toxic if inhaled or absorbed through the skin and is carcinogenic. Called also methanal and formic aldehyde.
Medical dictionary. 2011.