1To take advantage of someone or something; to exploit a weakness or opportunity.
詐欺師は高齢者の孤独につけ込んだ。
The con artist took advantage of the loneliness of the elderly.
ライバル会社の混乱につけ込んで契約を取った。
We exploited the rival company's confusion to win the contract.
弱みにつけ込むようなやり方は長続きしない。
A way of acting that preys on weaknesses won't last long.
2To enter (an item) in a ledger; to make an entry in accounts.
売上を売掛金として帳簿に付け込んだ。
I recorded the sales as accounts receivable in the ledger.
経費を正しく付け込まないと帳簿が合わなくなる。
If expenses aren't entered correctly, the books won't balance.