isobutane (?a?s??bju?te?n) n (Chemistry) chem a colourless gaseous hydrocarbon that is an isomer of butane and which is used as a fuel and a refrigerant. Formula: (CH3)3CHCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014i?so?bu?tane (?a? s??byu te?n, -byu?te?n) n. a colorless, flammable gas, C4H10, used as a fuel, a refrigerant, and in the manufacture of gasoline by alkylation. [1875?80] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.