filler metal n (General Engineering) metal supplied in the form of a welding rod, sometimes flux coated, melted by an arc or a flame into a joint between components to be joined Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014