Webster’s Revised Unabridged Dictionary · 1913
Invariable
In·va′ri·a·ble (ĭn·vā′rĭ·ȧ·b'l), 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.
In·va′ri·a·ble, n. (Math.) An invariable quantity; a constant.