thunder: [OE] 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’. => astound, detonate, stun, thursday, tornado
thunder (n.)
mid-13c., from Old English þunor "thunder, thunderclap; the god Thor," from Proto-Germanic *thunraz (cognates: Old Norse þorr, Old Frisian thuner, Middle Dutch donre, Dutch donder, Old High German donar, German Donner "thunder"), from PIE *(s)tene- "to resound, thunder" (cognates: Sanskrit tanayitnuh "thundering," Persian tundar "thunder," Latin tonare "to thunder"). Swedish tordön is literally "Thor's din." The intrusive -d- also is found in Dutch and Icelandic versions of the word. Thunder-stick, imagined word used by primitive peoples for "gun," attested from 1904.
thunder (v.)
13c., from Old English þunrian, from the source of thunder (n.). Figurative sense of "to speak loudly, threateningly, or bombastically" is recorded from mid-14c. Related: Thundered; thundering. Compare Dutch donderen, German donnern.