meth·ane (m?th??n?)n. An odorless, colorless, flammable gas, CH4, the major constituent of natural gas, that is used as a fuel and is an important source of hydrogen and a wide variety of organic compounds.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.methane (?mi??e?n) n (Elements & Compounds) a colourless odourless flammable gas, the simplest alkane and the main constituent of natural gas: used as a fuel. Formula: CH4. See also marsh gas, firedamp[C19: from meth(yl) + -ane]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014meth?ane (?m?? e?n; Brit. ?mi ?e?n) n. a colorless, odorless, flammable gas, CH4, the main constituent of marsh gas and the firedamp of coal mines, obtained commercially from natural gas: the first member of the alkane series of hydrocarbons. [1865?70] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.meth·ane (m?th??n?) A colorless, odorless, flammable gas that is the simplest of the hydrocarbons, having the formula CH4. It is the major constituent of natural gas and is released during the decomposition of plant or other organic compounds, as in marshes and coal mines.The American Heritage® Student Science Dictionary, Second Edition. Copyright © 2014 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.