Denshi Jisho — Online Japanese dictionary

轟轟 ごうごう 1:
2: (Usually written using kana alone) thunderous; rumbling; (Adverb taking the 'to' particle) thunderously; rumblingly
Na-adjective, Noun 
爆轟 ばくごう detonation
Noun, Suru verb 
轟轟 とどろとどろ thunderously; rumblingly
Adverb taking the 'to' particle 

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