Synonyms for False:

adj.

all (adjective)
mistaken.
arty (adjective)
imitative.
cowardly (adjective)
recreant.
deceptive (adjective)
delusive, illusive.
dishonest (adjective)
roguish, deceptive, lying, untrue.
dishonest, hypocritical (adjective)
base, corrupt, crooked, deceptive, dishonorable, disloyal, faithless, malevolent, malicious, mean, perfidious, rascally, recreant, traitorous, treacherous, treasonable, two-faced, underhanded, unfaithful, unscrupulous, untrustworthy, venal, villainous, Canting, Deluding, Forsworn.
erroneous (adjective)
botched, defective, distorted, illogical, marred, Misconceived, Misconstrued, miscalculated, misestimated, misjudged, erroneous, fallacious, faulty, flawed, inaccurate, incorrect, mistaken.
fake, counterfeit (adjective)
adulterated, alloyed, artificial, assumed, bum, colored, contrived, copied, disguised, factitious, feigned, forged, hollow, imitation, made-up, manufactured, meretricious, mock, pretended, pseudo, simulated, so-called, synthetic, wrong.
false (adjective)
crooked, deceptive, dishonest, fictional, made-up, phony, unsound, Deluding, Truthless, bogus, counterfeit, deceitful, fraudulent.
fictitious (adjective)
fictional, trumped-up.
mendacious (adjective)
mendacious.
pretended (adjective)
assumed, feigned.
pretentious (adjective)
affected, artificial, bogus, counterfeit, deceitful, ersatz, facade, fake, forced, forged, fraudulent, histrionic, imitation, imposture, la-di-da, mannered, mock, ostentatious, overdone, posing, pretentious, showy, stagy, stiff, stilted, studied, synthetic, theatrical, unnatural, Impersonating, Masquerading.
unrecognizable (adjective)
disguised.
untruthful (adjective)
untruthful.
wrong (adjective)
aberrant, bad, erroneous, fallacious, faulty, flawed, illegal, improper, inaccurate, incorrect, mistaken, untrue, wrong.
wrong, made up (adjective)
apocryphal, bogus, counterfactual, deceitful, delusive, dishonest, distorted, erroneous, ersatz, fake, fallacious, fanciful, faulty, fictitious, fishy, fraudulent, illusive, imaginary, improper, inaccurate, incorrect, invalid, lying, mendacious, misleading, mistaken, phony, sham, specious, spurious, unfounded, unreal, unsound, untrue, untruthful.

n.

base, corrupt, disingenuous, disloyal, faithful, faithless, hypocritical, knavish, lying, malevolent, malicious, mean, perfidious, rascally, roguish, seditious, sugary, traitorous, treacherous, treasonable, true, two-faced, underhanded, unfaithful, unscrupulous, untrustworthy, untruthful, venal, villainous, Canting, Double dealing, Forsworn. accurate, alleged, allegedly, anecdotal, apocryphal, apparently, correct, doubtful, fanciful, fishy, illusive, imaginary, misleading, seemingly, speculative, spurious, supposed, unfounded, unsubstantiated. adulterated, alloyed, approximate, approximately, authentic, broadly, bum, colored, contrived, copied, disguised, factitious, feigned, genuine, gyp, imprecise, lifeless, made-up, manufactured, meretricious, pseudo, questionable, real, roughly, shoddy, so-called, make believe. counterfactual, hypothetical. unsound. sophistic. suppositious, supposititious. continue, recreant, trust, False-hearted. cheat (noun)
betray, deceive, trick.
false (noun)
artificial, assumed, counterfeit, delusive, dishonest, dishonorable, faithlessly, fake, faux, fictitious, fictive, hollow, imitation, imitative, inconstant, incorrect, inharmonious, insincere, invalid, mendacious, mistaken, off-key, pretended, sham, simulated, sour, specious, traitorously, treacherously, treasonably, trumped-up, unharmonious, unreal, unrealistic, untrue, wrong, put on.
imitation (noun)
pseudo.

v.

deceiving (verb)
hypocritical.
pretended (verb)
make believe.

Other synonyms:

counterfactual, disingenuous, faithless, hypothetical, imaginary, sophistic, sugary, unfaithful, Canting, False-hearted. perfidious. colored, lying. counterfeit
spurious, suppositious.
deceitful
two-faced.
perfidious
disloyal.
simulated
feigned, simulated.
spurious
apocryphal.
traitorous
treacherous.
treacherous
traitorous.
unconfirmed
unsubstantiated.
unnatural
factitious.
untrue
untruthful.
Other relevant words:
adulterated, alleged, allegedly, alloyed, anecdotal, apocryphal, apparently, approximate, approximately, assumed, authentic, base, betray, broadly, bum, colored, continue, contrived, copied, correct, corrupt, counterfactual, deceive, delusive, disguised, dishonorable, disingenuous, disloyal, doubtful, factitious, faithful, faithless, faithlessly, fanciful, faux, feigned, fictitious, fictive, fishy, genuine, gyp, hollow, hypocritical, hypothetical, illusive, imaginary, imitative, imprecise, inconstant, inharmonious, insincere, invalid, knavish, lifeless, lying, made-up, malevolent, malicious, manufactured, mean, mendacious, meretricious, misleading, off-key, perfidious, pretended, pseudo, questionable, rascally, real, recreant, roguish, roughly, seditious, seemingly, sham, shoddy, simulated, so-called, sophistic, sour, specious, speculative, spurious, sugary, supposed, suppositious, supposititious, traitorous, traitorously, treacherous, treacherously, treasonable, treasonably, trick, true, trumped-up, trust, two-faced, underhanded, unfaithful, unfounded, unharmonious, unreal, unrealistic, unscrupulous, unsound, unsubstantiated, untrustworthy, untruthful, venal, villainous, Canting, Double dealing, False-hearted, Forsworn, put on.

Usage examples for false

  1. If the old man's memory ever played him false his imagination never failed him. – A Chapter of Adventures by G. A. Henty
  2. She was faithful when I was false was she not? – Shirley by Charlotte Brontë
  3. When Juan met the false friend again, the false friend asked him what gift he had this time. – Philippine Folk-Tales by Clara Kern Bayliss, Berton L. Maxfield, W. H. Millington, Fletcher Gardner, Laura Watson Benedict