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brains; brain tissue
幽霊よりも生きている人間の脳味噌のほうが怖い。
The human brain is scarier than any ghost.
事故の衝撃で脳味噌が飛び出すほどの激しさだった。
The impact of the accident was so violent it felt like brains would fly out.
もっと脳味噌を使って考えてほしい。
I want you to use your brain and think more.