abandoned adamant afire ardent assiduous bent bold bound bound and determined bulldog bulldoggish burning changeless committed constant continuing dauntless decided decisive dedicated definite deliberate determined devoted devout diligent dogged earnest enduring experimental faithful fast fervent fervid fiery firm flaming game gamy gritty gutsy gutty hearty heated hot hot-blooded immutable impassioned in earnest inalterable indefatigable indomitable industrious inflexible insistent intense intent intent on invincible irreversible lasting loyal mettlesome nervy never-tiring obstinate on fire passionate patient patient as Job perfervid permanent perseverant persevering persistent persisting pertinacious plodding plucky plugging preoccupied purposeful purposive rapt red-blooded red-hot relentless resolved sedulous serious set settled sincere single-minded sleepless slogging spirited spiritful spunky stable staunch steadfast steady stubborn tenacious tentative tireless tough trial TRUE unabating unalterable unchangeable unchanging unconquerable undaunted undeviating undiscouraged undrooping unfailing unfaltering unflagging unflinching unhesitant unhesitating unintermitting uninterrupted unnodding unrelaxing unrelenting unremitting unshakable unshakeable unshaken unsleeping unswerving untiring unwavering unwearied unwearying unwinking utterly attentive vehement venturesome warm weariless white-hot wholehearted willing zealous