Abarim Publications' online Biblical Greek Dictionary
The noun βροντη (bronte) means both thunder (the rumble that comes after lightning) and the state of one struck with sudden insight: astonishment, or in the words of Maimonides: perplexity (Guide For The Perplexed, 1190). It stems from the Proto-Indo-European root "brem-", to make noise (hence also the ever useful Dutch verb brommen).
Thunder, and thus being thunder-struck, is widely associated with the divine: the primary attributes of gods like Thor (hence our Thursday), Zeus and Hadad were thunder and lightning (αστραπη, astrape, lightning). Julius Caesar's pet legion was Legio XII Fulminata, Legion Twelve Thunderstruck. The Brontë family (Emily, Wuthering Heights, 1847) derived their name from our noun, and neither ACDC nor Imagine Dragons sang of physical thunder.
As part of the cache unearthed in Nag Hammadi in 1945, the poem The Thunder, Perfect Mind demonstrates that, at least to the Gnostic tradition, thunder was closely associated to the intellectual mind of humanity. Or in the words of Jesus through Luke: "For the Son of Man in his day will be like the lightning, which flashes and lights up the sky from one end to the other" (Luke 17:24).
In the Bible, thunder is most associated with the קול (qol), or Voice from Heaven (John 12:29). As the Psalmist says: "The Voice of YHWH twists the oaks and strips the forests bare. And in his temple all cry, "Glory!" " (Psalm 29:9). Although our noun βροντη (bronte) does not occur in the scene that describes Paul's conversion on the road to Damascus, thunder and lightning are obviously implied (Acts 9:3-7).
Significantly, the New Testament depicts the Logos as divine, eternal and unchanging, but the Word in the Flesh (the human incarnation of the Logos) as an emergent property of society — hence the Virgin Birth (see our article on παρθενος, parthenos, virgin) and the waxing Child (Isaiah 7:14-16, Luke 2:40, 2:52). Since the incarnated Logos is an emergent property of society, and society consists of individuals that approach each other in discourse and negotiation, the incarnated Word also appears on clouds — that is: clouds of witnesses (Hebrews 12:1); see our article on the noun νεφελη (nephele), cloud. Hence the word thunder not only applies to the sound of lightning coming out of clouds of suspended water vapor, also of roaring rivers (see our article on Tigris) and cheering crowds (Revelation 19:6).
The familiar term Sons of Thunder (Mark 3:17) appears to have been a generic term, but see our article on the name Boanerges for more on this. Our noun βροντη (bronte) appears 12 times in the New Testament; see full concordance.