Invariable

In‐va″ri‐a‐ble (?), a. [Pref. in- not + variable: cf. F. invariable.] Not given to variation or change; unalterable; unchangeable; always uniform.

Physical laws which are invariable. I. Taylor.

— In‐va″ri‐a‐ble‐ness, n. — In‐va″ri‐a‐bly, adv.