oxo-
or before a vowel ox-
combining form (Chemistry) indicating that a chemical compound contains oxygen linked to another atom by a double bond, used esp to denote that a compound is derived from a specified compound by replacement of a methylene group with a carbonyl group: oxobutanoic acid.
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014