The Collaborative International Dictionary of English v.0.48:

Persistent \Per*sist"ent\, a. [L. persistens, -entis, p. pr. of
   persistere. See Persist.]
   1. Inclined to persist; having staying qualities; tenacious
      of position or purpose.
      [1913 Webster]

   2. (Biol.) Remaining beyond the period when parts of the same
      kind sometimes fall off or are absorbed; permanent; as,
      persistent teeth or gills; a persistent calyx; -- opposed
      to deciduous, and caducous.
      [1913 Webster]

WordNet (r) 3.0 (2006):

persistent
    adj 1: never-ceasing; "the relentless beat of the drums" [syn:
           persistent, relentless, unrelenting]
    2: continually recurring to the mind; "haunting memories"; "the
       cathedral organ and the distant voices have a haunting
       beauty"- Claudia Cassidy [syn: haunting, persistent]
    3: retained; not shed; "persistent leaves remain attached past
       maturity"; "the persistent gills of fishes" [syn:
       persistent, lasting] [ant: caducous, shed]
    4: stubbornly unyielding; "dogged persistence"; "dour
       determination"; "the most vocal and pertinacious of all the
       critics"; "a mind not gifted to discover truth but tenacious
       to hold it"- T.S.Eliot; "men tenacious of opinion" [syn:
       dogged, dour, persistent, pertinacious, tenacious,
       unyielding]

Moby Thesaurus II by Grady Ward, 1.0:

245 Moby Thesaurus words for "persistent":
   abiding, accordant, adherent, adhesive, age-long, aged, alike,
   ancient, antique, archaic, assiduous, automatic, balanced, beaten,
   booming, bound, bound and determined, bulldogged, bulldoggish,
   bulldoggy, bullheaded, changeless, chronic, clamant, clamorous,
   clingy, committed, consistent, consonant, constant, continual,
   continuing, continuous, correspondent, crying, decided, decisive,
   dedicated, definite, demanding, determined, devoted, diligent,
   diuturnal, dogged, draining, durable, earnest, echoic, echoing,
   enduring, equable, equal, even, evergreen, exacting, exigent,
   exorbitant, extortionate, faithful, fast, firm, fixed, flat,
   frequent, frozen, gluey, glutinous, grasping, growling, gummy,
   habitual, hackneyed, hardy, haunting, homogeneous, immobile,
   immutable, importunate, inalterable, incessant, indefatigable,
   indelible, indomitable, industrious, inflexible, insistent,
   instant, intact, interminable, intransient, invariable, inveterate,
   invincible, inviolate, lasting, level, lingering, long-lasting,
   long-lived, long-standing, long-term, longeval, longevous, loud,
   loyal, macrobiotic, measured, mechanical, methodic, monolithic,
   nagging, never-tiring, obdurate, obsessive, obstinate, of a piece,
   of long duration, of long standing, ordered, orderly, patient,
   patient as Job, perdurable, perduring, perennial, permanent,
   perpetual, perseverant, persevering, persisting, pertinacious,
   plodding, plugging, preoccupied, pressing, purposeful, quiescent,
   rapt, reboant, rebounding, recurrent, recurring, reechoing,
   regular, relentless, remaining, repercussive, repetitive, resolute,
   resolved, resounding, reverberant, reverberating, reverberatory,
   rigid, robotlike, routine, rumbling, sedulous, self-adhesive,
   sempervirent, serious, sincere, single-minded, sleepless, slogging,
   smooth, solid, sounding, stable, static, stationary, staunch,
   staying, steadfast, steady, stereotyped, stickable, sticking,
   sticky, stubborn, sustained, systematic, tacky, taxing, tenacious,
   thundering, tireless, torpid, tough, trite, unabating, unaltered,
   unbroken, unceasing, unchangeable, unchanged, unchanging,
   unchecked, unconquerable, undamped, undaunted, undestroyed,
   undeveloped, undeviating, undifferentiated, undiscouraged,
   undiversified, undrooping, undying, unending, unfading, unfailing,
   unfaltering, unflagging, unflinching, unforgettable, uniform,
   unintermitting, uninterrupted, unnodding, unrelaxing, unrelenting,
   unremitting, unruffled, unshakable, unshifting, unsleeping,
   unswerving, untiring, unvaried, unvarying, unwavering, unwearied,
   unwearying, unwinking, urgent, utterly attentive, viscid, vital,
   weariless, well-trodden, well-worn, wholehearted



The Free On-line Dictionary of Computing (30 December 2018):

persistence
persistent

   1.  A property of a programming language where
   created objects and variables continue to exist and retain
   their values between runs of the program.

   2.  The length of time a phosphor dot on the screen
   of a cathode ray tube will remain illuminated after it has
   been energised by the electron beam.  Long-persistence
   phosphors reduce flicker, but generate ghost-like images that
   linger on screen for a fraction of a second.

   (1994-11-09)