1.
immovable; steadfast; unshakeable
Something that does not move or cannot be moved. Used both literally (not moving physically) and figuratively (firm, unwavering, established beyond doubt).
Frequently used as a modifier with の: 不動の地位 (unshakeable position), 不動の人気 (unwavering popularity). In sports, 不動のレギュラー means an undisputed regular player.
Also appears in the Buddhist term 不動明王 (Acala), one of the Wisdom Kings who is depicted with an immovable, fierce expression.
The compound 不動産 (real estate, lit. "immovable property") is derived from this word.