A large sum of money; a great amount of money or high cost.
宝くじで大金を手に入れたらどうする？
What would you do if you got a large sum of money from the lottery?
彼は会社のために大金を寄付した。
He donated a large sum to the company.
大金が必要なので、家を担保にした。
Because a large sum was needed, I used my house as collateral.