/meth"ayn/ ; Brit. /mee"thayn/ , n. Chem.
a colorless, odorless, flammable gas, CH 4 , the main constituent of marsh gas and the firedamp of coal mines, obtained commercially from natural gas: the first member of the methane, or alkane, series of hydrocarbons.
[ 1865-70; METH- + -ANE ]