Young's modulus Syllabification: (Young's mod·u·lus)Pronunciation: /ˈyəNGz/Definition of Young's modulus noun Physics a measure of elasticity, equal to the ratio of the stress acting on a substance to the strain produced. Origin: mid 19th century: named after T. Young (see Young, Thomas)Young's modulus in other Oxford dictionaries Definition of Young's modulus in the British & World English dictionary