Other forms: thundering, thunders
Thunder is the huge rumbling sound that follows the flash in a storm. Lightning heats the air so fast that it bangs.
Because light travels faster than sound, counting the seconds between the flash and the thunder tells you roughly how far off the storm is. The word is a mass noun, so there is a lot of thunder rather than many thunders. As a verb it covers any deep rolling noise, since lorries thunder past and a crowd can thunder. Stealing somebody's thunder means taking the attention they had earned.
1nounthunderThe loud rumbling sound that follows lightning.
“There was thunder over the hills all evening.”
2verbmoveTo move or sound with a deep rolling noise.
“A lorry thundered past the window.”
Too few real examples of this word to estimate which sense is commonest.
Thunder is named by imitation. The Proto-Indo-European root meant to thunder, and Old English þunor is that sound written down; the word has been onomatopoeia the whole way through.
Proto-Indo-European
*(s)tenh₂-
Proto-Indo-European
*(s)ten-
Proto-Germanic
*þunraz
Proto-West Germanic
*þunr
Old English
þunor — thunder
Middle English
thunder
English, today
thunder
Built from
From Middle English thunder, thonder, thundre, thonre, thunnere, þunre, from Old English þunor (“thunder”), from Proto-West Germanic þunr, from Proto-Germanic þunraz, from Proto-Indo-European (s)ten-, (s)tenh₂- (“to thunder”). Compare astound, astonish, stun. Germanic cognates include West Frisian tonger, Dutch donder, German Donner, Old Norse Þórr (English Thor), Danish torden, Norwegian Nynorsk tore. Other cognates include Persian تندر, Latin tonō, detonō, Ancient Greek στένω, στενάζω, στόνος, Στέντωρ, Irish torann, Welsh taran, cel-gau Taranis. a doublet of donner and Thunor and Thor.
Etymology from Wiktionary, CC BY-SA