False
WordNet
adjective
(1) (used especially of persons) not dependable in devotion or affection; unfaithful
"A false friend"
"When lovers prove untrue"
(2) Arising from error
"A false assumption"
"A mistaken view of the situation"
(3) Adopted in order to deceive
"An assumed name"
"An assumed cheerfulness"
"A fictitious address"
"Fictive sympathy"
"A pretended interest"
"A put-on childish voice"
"Sham modesty"
(4) Inaccurate in pitch
"A false (or sour) note"
"Her singing was off key"
(5) Designed to deceive
"A suitcase with a false bottom"
(6) Not genuine or real; being an imitation of the genuine article
"It isn't fake anything; it's real synthetic fur"
"Faux pearls"
"False teeth"
"Decorated with imitation palm leaves"
"A purse of simulated alligator hide"
(7) Inappropriate to reality or facts
"Delusive faith in a wonder drug"
"Delusive expectations"
"False hopes"
(8) Deliberately deceptive
"Hollow (or false) promises"
"False pretenses"
(9) Not in accordance with the fact or reality or actuality
"Gave false testimony under oath"
"False tales of bravery"
(10) Erroneous and usually accidental
"A false start"
"A false alarm"
adverb
(11) In a disloyal and faithless manner
"He behaved treacherously"
"His wife played him false"
WiktionaryText
Etymology
From false from fals "false, fraud, falsehood" from , falsus "counterfeit, false, falsehood" from fallere "to deceive". Uncommon before the 12 century, the word was reinforced in by fals (cf faus). Displaced native les, lese "false" from lēas. More at leasing