1Something treasured and carefully kept or the act of treasuring/keeping it hidden; often seen in phrases like 'secretly treasured (item)'.
彼は秘蔵のフィギュアをケースから出して見せてくれた。
He took out his treasured figure from the case and showed it to me.
その店は秘蔵のワインを客のために特別に出した。
The shop served a specially reserved (treasured) wine for the customer.
映画監督が長年の秘蔵映像を公開した。
The film director released long-kept treasured footage.