ageless arrowlike articulated assiduous catenated ceaseless chattering coeternal concatenated connected consecutive consistent constant continual continued continuing continuous cyclical dateless dead straight diligent direct dogged endless enduring eternal eterne even ever-being ever-durable ever-during everlasting everliving faithful featureless flat gapless horizontal immediate immemorial immutable in a line inalterable incessant indefatigable indestructible indomitable industrious infinite insistent interminable invincible irreversible joined jointless lasting level lineal linear linked loyal machine gun monotonous never-ceasing never-ending never-tiring nonstop nonterminating nonterminous obstinate olamic one-way orderly oscillating patient patient as Job perdurable perennial periodic permanent perpetual perseverant persevering persistent persisting pertinacious plodding plugging preoccupied pulsating rapid rapt rectilineal rectilinear recurrent regular relentless repeated repetitive resolute right round-the-clock ruler-straight running seamless sedulous sempiternal sequent sequential serial serried single-minded sleepless slogging smooth stable staccato steadfast steady straight straight-cut straight-front straight-side straightaway straightforward straightway streamlined stubborn stuttering sustained tenacious through tight timeless tireless TRUE twenty-four-hour unabating unbending unbent unbowed unbroken unceasing unchanging unconquerable uncurved undaunted undeflected undeviating undifferentiated undiscouraged undistorted undrooping unending unfailing unfaltering unflagging unflinching unidirectional uniform unintermitted unintermittent unintermitting unnodding unrelaxing unrelenting unrelieved unremitting unsleeping unstopped unswerving untiring unturned unvarying unwavering unwearied unwearying unwinking upright utterly attentive vertical vibrating weariless without end