水すい素そ爆ばく弾だんすいそばくだんMeanings1nounhydrogen bombA nuclear weapon using hydrogen fusion; often contrasted with 原子爆弾 (atomic bomb). The abbreviation 水爆 is also common.See also: 水爆水すい素そ爆ばく弾だんは原げん子し爆ばく弾だんよりはるかに強