ground-breaking adjective 1noun 1forms 3 adjective1 •innovative, different than other things of its type.There were papers such as John Aspinall's presidential address about his ground-breaking work on railway electrification in 1909 [...]. — 2019 noun1 •A ceremony marking the commencement of construction of a road, bridge, or building.I HAVE had a hand in numerous ground breakings and ribbon cuttings, but never before have I approached one with the eagerness and enthusiasm that I possess for today's ceremony. — 1960 formsground-breakings · more ground-breaking · most ground-breaking