groundbreaking /ˈɡɹaʊndˌbɹeɪkɪŋ/noun 2adjective 1forms 3 noun2 •The point at which construction begins, by digging into the ground. •A ceremony to mark the beginning of construction. adjective1 •Innovative; new, different; doing something that has never been done before.The latest model includes several groundbreaking features and improvements. formsgroundbreakings · more groundbreaking · most groundbreaking