the original; original item
Refers to the actual physical object itself, as opposed to a copy, reproduction, or representation. Often used in contexts like art, documents, or specimens.
この絵は原物と見分けがつかないほど精巧な複製だ。
This painting is such an exquisite reproduction that it's indistinguishable from the original.
契
The original of the contract is kept in the safe.