arrowlike, assiduous, constant, continuing, dead straight, diligent, direct, dogged, enduring, even, faithful, firm, fixed, flat, flinty, horizontal, immediate, immovable, immutable, in a line, inalterable, indefatigable, indomitable, industrious, inflexible, insistent, invincible, irreversible, lasting, level, lineal, linear, loyal, never-tiring, obstinate, one-way, patient, patient as Job, permanent, perseverant, persevering, persistent, persisting, pertinacious, plodding, plugging, preoccupied, rapt, rectilineal, rectilinear, relentless, resolute, right, ruler-straight, sedulous, set, settled, single-minded, sleepless, slogging, smooth, sot, stable, staunch, steadfast, steady, steely, straight-cut, straight-front, straight-side, straight, straightaway, straightforward, straightway, streamlined, stubborn, tenacious, tireless, true, unabating, unbending, unbent, unbowed, unbroken, unconquerable, uncurved, undaunted, undeflectable, undeflected, undeviating, undiscouraged, undistorted, undrooping, unfailing, unfaltering, unflagging, unflappable, unflinching, unidirectional, unintermitting, uninterrupted, unnodding, unrelaxing, unrelenting, unremitting, unshaken, unsleeping, untiring, unturned, unwavering, unwearied, unwearying, unwinking, unyielding, upright, utterly attentive, vertical, weariless