blackline noun 2verb 1forms 3 noun2 •A document indicating the differences between two versions of another document. •A line of deliberately burned material created to stop the advance of a larger fire.A second squad uses drip torches to begin burning a 15- to 20-foot barrier or “blackline” inside the wetline. — 2011 verb1 •To compare versions of (a document) by this method. formsblacklined · blacklining · blacklines
