biodiesela fuel similar to diesel that is made from vegetable oil Abused, Confused, & Misused Words by Mary Embree Copyright © 2007, 2013 by Mary Embreebi·o·die·sel (b???-d??z?l, -s?l)n. A biofuel made by processing vegetable oils and other fats for use in a diesel engine, either in pure form or as an additive to conventional diesel fuel.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.biodiesel (?ba????di?z?l) n (Automotive Engineering) a biofuel intended for use in diesel enginesCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014