Gustav Hertz gus·tav·hertz uncommon noun 1. German physicist who with James Franck proved the existence of the stationary energy states postulated by Bohr (1887-1975) SynonymsHertzGustav HertzGustav Ludwig Hertz Related words Broader terms nuclear physicist WordNet 2.1 (Princeton University). WordNet 2.1 Copyright Princeton University. All rights reserved.