Unopened; sealed. Describes something (like a package or envelope) whose seal has not been broken and remains in its original state.
プレゼントは未開封のまま保管してください。
Please keep the present unopened.
未開封の商品は返品ポリシーの対象外です。
Unopened items are excluded from the return policy.
箱は開けたけれど、個別の包装はまだ未開封だ。
I opened the box, but the individual packaging is still unopened.