- noun a loud sound generated by lightning in the atmosphere
- noun the noise created by the violent expansion and contraction of air momentarily heated by a lightning discharge
- The sonic boom heard as a consequence of the shock waves produced by the explosive expansion of the air surrounding a lightning discharge.
Origin & History of “thunder”
Etymologically, thunder is nothing more than ‘noise’. In common with German donner, Dutch donder, and Danish torden, it goes back to a prehistoric Germanic *thonara-. this was descended from the Indo-European base *ton-, *tn- ‘resound’, which also produced the Latin verb tonāre ‘thunder’ (source of English astound, detonate, and stun) and the Latin noun tonitrus ‘thunder’ (source of French tonnerre ‘thunder’). Thursday is etymologically the ‘day of thunder’.