Entry 2 senses Webster, 1913 Thunderous /thŭn'-dẽr-əs/ · Thun·der·ous · IPA /ˈθʌn.dɚ.əs/ 01 a. Producing thunder. 1. Producing thunder.[R.] “How he before the thunderous throne doth lie.” — Milton. 2. Making a noise like thunder; sounding loud and deep; sonorous.