(a.) Not alterable; incapable of being altered or changed; unalterable.

assiduous constant continuing diligent dogged enduring faithful fixed immovable immutable indefatigable indomitable industrious insistent invariable invincible lasting loyal never-tiring obstinate patient patient as Job permanent perseverant persevering persistent persisting pertinacious plodding plugging preoccupied rapt relentless resolute sedulous single-minded sleepless slogging stable steadfast steady stubborn tenacious tireless unabating unalterable unchangeable unconquerable undaunted undiscouraged undrooping unfailing unfaltering unflagging unflinching unintermitting uninterrupted unmodifiable unmovable unnodding unrelaxing unrelenting unremitting unsleeping unswerving untiring unwavering unwearied unwearying unwinking utterly attentive weariless