testing /ˈtɛs.tɪŋ/noun 1adjective 1forms 3phrases 1 noun1 •the act of checking carefully how well something works or how much someone knowsThe wilderness testings of Jesus prepare him for ministry in which such temptations and shortcuts will recur. — 2011 adjective1 •Difficult; tough.A testing time lies ahead for the new administration. formstestings · more testing · most testing Phrases with testing wind tunnel testingThe application of a rigorous testing regime to a new corporate idea, structure or project to determine if it is viable and fit for purpose.