/ fɔːˈmældɪhaɪd; NAmE fɔːrˈm-/ noun [ U ]
1.
( symb CH 2 O ) a gas with a strong smell
2.
(also technical for·mal·in / ˈfɔːməlɪn; NAmE ˈfɔːrm-/) a liquid made by mixing formaldehyde and water, used for preserving biological specimens , making plastics and as a disinfectant
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WORD ORIGIN
late 19th cent.: blend of formic acid and aldehyde .