Archaic adverb describing a loud, deep, reverberating sound such as thunder, waves, or a crowd. In modern Japanese, the onomatopoeic ゴロゴロ or the verb 轟く (とどろく) are more common.
In classical texts, it was used like 'the thunder roars with a rumble.'
The thunder roared and echoed through the sky.
ゴロゴロ is a common, colloquial onomatopoeia for rumbling or rolling sounds, much more casual and current than the archaic 轟.
roar; thunder; boom; rumble; resound · become famous; become well known · pound; throb; palpitate
roar; rumble; booming · beating; pounding; throbbing
todorokite
make a thundering sound; let resound · make widely known; spread one's name · make one's heart pound; throb; thump
The exact derivation is uncertain; the kanji 轟 is conventionally associated with loud rumbling sounds, and the reading とどろ is related to the verb 轟く (とどろく).