noun
title deed; certificate of title
A legal document proving ownership of real estate or other registered property. Used in formal and administrative contexts.
不動産を購入したら、権利書を大切に保管してください。
When you purchase real estate, please keep the title deed in a safe place.
権利書がないと、所有権を証明できません。
Without the certificate of title, you cannot prove ownership.
権利証 is a synonym often used in the same legal contexts; 権利書 is slightly more common in everyday references to the document.
Compound of 権利 (right, claim) and 書 (document, writing). The term is a straightforward legal compound with no obscure historical derivation.