Possession or ownership. As a noun it can mean a storehouse; as a suffix it appears in words meaning private possession (e.g., 秘蔵).
彼は秘蔵のコレクションを公開した。
He revealed his cherished/private collection.
蔵に古い書物が眠っている。
Old books lie stored in the warehouse.
美術館は市民の蔵から寄贈を受けた。
The museum received donations from citizens' collections.
An abbreviated usage referring to Tibet (as in 西蔵).
西蔵（チベット）は高地に広がる地域だ。
Tibet (西蔵) is a region spread over the highlands.