Synonyms for Faithful:

adj.

accurate (adjective)
careful, correct, specific, rigorous, solid, unerring, authentic.
all (adjective)
close.
authentic (adjective)
convincing, accurate, reliable, authoritative, certain, valid.
conscientious (adjective)
tough, diligent.
constant (adjective)
persevering, unflagging, dogged.
convincing (adjective)
hopeful.
faithful (adjective)
constant, genuine, affectionate, right, steadfast, sincere, true, lifelike, trustworthy, dutiful, sure, obedient, firm, attached, unswerving, loving, allegiant, precise, resolute, exact, honest, strict, devoted, veridical, unchanging, trusty, scrupulous, tried and true, unwavering, close, credible, fast, dependable, enduring, conscientious, true-blue, staunch, honorable, straight, upright, patriotic, steady, confiding, veracious.
hopeful (adjective)
eager, aspiring, desirous, sure, expectant, hopeful, optimistic, yearning.
lifelike (adjective)
lifelike, exact, realistic, vivid, natural.
loving (adjective)
amorous, desirous, adoring, intimate, romantic, cherishing, tender, sentimental, fond, passionate, friendly, erotic, worshipful, devoted, affectionate, admiring, endearing, loving, caring, infatuated.
obedient (adjective)
devoted, servile, submissive, dutiful, allegiant, loyal, compliant, meek, acquiescent, obedient.
orthodox (adjective)
conforming, dogmatic, religious, ideological, orthodox, traditional, believing.
perfect (adjective)
perfect.
persuasive (adjective)
convincing.
pious (adjective)
dutiful, dogmatic, godly, christian, reverent, devoted, cultist, worshipful, superstitious, solemn, religious, prayerful, obedient, sanctified, devout, sanctimonious, holier-than-thou, pious, holy.
precise (adjective)
accurate.
reliable (adjective)
conscientious, certain, reliable, devoted, dependable, trustworthy, trusty, loyal.
reputable (adjective)
honorable.
resolute (adjective)
dedicated, zealous, headstrong, thorough, iron-willed, reliable, stubborn, decisive, unbending, firm, plucky, resolved, unyielding, hearty, resolute, relentless, decided, steady, dogged, spunky, tough, persevering, diligent, valiant, devoted, willing, indomitable, deliberate, insistent, implacable, staunch, steadfast, intent, stern, set, strong-willed, unchangeable, committed, loyal, unflinching, indefatigable, determined, true, courageous, bullheaded, unshakeable, strong-minded, uncompromising, constant, unwavering, steely, fearless, persistent, dauntless, tenacious, tireless, earnest, inexorable, serious, bold, ruthless.
tenacious (adjective)
brave, decisive, bulldogged, strong-willed, spunky, dogged, obdurate, tireless, dauntless, flintlike, undaunted, strong, indefatigable, bold, enduring, devoted, persistent, fervent, stubborn, persevering, steadfast, bullheaded, determined, resolute, plucky, stony, stiff, true, tough, headstrong, staunch, diligent, obstinate, hard, insistent, hearty, indomitable, unflagging, tenacious, courageous.
true (adjective)
truehearted.
true-blue (adjective)
true-blue.
trusting (adjective)
trusting, sure, confident, believing.
veracious (adjective)
veracious.
veridical (adjective)
veridical.

n.

specific, unerring, perfect. affair, adultery, cheat, deceive, bigamy, adulterous, cuckold, continue, Adulterer, cheat on, trust, liege. authoritative, convincing, credible, independent, bipartisan, coalition, front, apolitical, liberal, ministerial, the faithful, dissident, authentic, nationalist, valid. careful, ascetic, strict, rigorous, full, observant, puritanical, spiritual. beg, howl, precise, right, correct, honest, retrieve, bark, slaver, snap, wag, real, bay, veracious, veridical. faithful (noun)
fast, true, true to, truehearted, close, firm, congregation, fold, accurate, loyal.
loyal (noun)
genuine, veracious, unswerving, upright, at the feet of, firm in adherence, honorable, scrupulous, solid, patriotic, honest, stalwart, sincere, diehard, straight, attached, true-blue, unchanging, supportive, trusted, hard core, true as steel, confiding, tried and true.

Other synonyms:

liege, authentic, veridical, wag, strict. convincing, credible, valid, retrieve, slaver, veracious, beg. precise, snap, howl, rigorous. authoritative. right. full. devoted
hard core.
honest
sincere.
loyal
solid, true-blue, diehard, stalwart.
trustworthy
trusted.

Usage examples for faithful

  1. He is a good and faithful boy." – Andy Grant's Pluck by Horatio Alger
  2. " And remember," she wrote at the close, " remember that sooner than see you very unhappy, I will marry you, will try to be a faithful wife; though, Henry, I would rather not- oh, so much rather not!" – Maggie Miller by Mary J. Holmes
  3. A generous master makes faithful servants. – Lost in the Cañon by Alfred R. Calhoun