Affixing a seal (to a document); stamping; putting one's seal (on) (essentially same as 押印).
契約書に捺印してからコピーをお渡しします。
I'll give you a copy after I affix my seal to the contract.
重要書類には必ず捺印が必要だ。
Important documents always require a seal.
役所の窓口で書類に捺印を求められた。
At the municipal office counter I was asked to put my seal on the document.