noun
marginal seal; approval seal in the margin
A seal stamped in the margin of a contract or official document in advance, to validate later handwritten corrections or additions without needing a new seal each time.
契約書の余白に捨て印を押しておくと、後から訂正するときに便利だ。
If you stamp a marginal seal on the contract in advance, it's convenient when you need to make corrections later.
noun
using up leftover ink on a seal
The act of pressing a seal onto scrap paper to remove excess ink after inking, so the next impression is clean. Less common than the marginal seal sense.
朱肉をつけすぎたので、捨て印をしてから書類に押した。
I put too much ink on the seal, so I blotted it on scrap paper before stamping the document.
訂正印 is a seal used to indicate a specific correction after the fact, while 捨て印 is pre-stamped to allow future corrections.
認印 is a general personal seal for everyday use, not specifically for document margins or ink removal.
Compound of 捨て (sute, 'discard' or 'throw away') + 印 (in, 'seal'). The term likely originates from the idea of a seal that is 'thrown away' in the margin, or from the practice of discarding excess ink.