false / fôls/ • adj. 1. not according with truth or fact; incorrect: false results the allegations were false. ∎  not according with rules or law: false imprisonment.2. deliberately made or meant to deceive: the trunk has a false bottom a false passport. ∎  artificial: false eyelashes. ∎  feigned: a horribly false smile.3. illusory; not actually so: sunscreens give users a false sense of security.4. treacherous; unfaithful: a false lover.DERIVATIVES: false·ly adv.false·ness n.fal·si·ty / ˈfôlsətē/ n.

false false friend a word or expression that has a similar form to one in a person's native language, but a different meaning (for example English magazine and French magasin ‘shop’).
false memory an apparent recollection of an event which did not actually occur, especially one of childhood sexual abuse arising from suggestion during psychoanalysis; in the 1990s the question of whether buried memory of this kind could be recovered through psychoanalysis was strongly debated, with proponents of the theory using the term recovered memory to demonstrate the belief that such recollections could be rooted in fact.
false position a situation in which one is compelled to act in a manner inconsistent with one's true nature or principles.
play someone false deceive or cheat someone.

see also sail under false colours.

false wrong; untrue, deceitful; spurious, OE. fals adj. in false ġewihta wrong weights, falspening counterfeit penny (cf. ON. falspeningr) and sb. ( = ON. fals) ‘fraud, deceit, falsehood’ — L. falsus adj. and falsum n. sb., prop. pp. of fallere deceive. In ME. reinforced by or newly — OF. fals, faus, fem. false (mod. faux, fausse) :- L. falsus, -a.
Hence falsehood XIV. falsify XV. — F. or late L. falsity XVI. — L. falsitās; cf. ME. fals(e)te treachery, fraud — OF. falseté (mod. fausseté).

false. Anything that seems to be what it is not, such as a false or pseudo-arch, false Attic (wall concealing a roof, but not containing rooms), false door, or false front (façade extending beyond the side walls and/or roof of the building to make a building seem grander than it is).