falser

1. Untrue, not factual, factually incorrect.
2. Based on factually incorrect premises.

   false legislation, false punishment

3. Spurious, artificial.

   false teeth

4. Of a state in Boolean logic that indicates a negative result.
5. Uttering falsehood; dishonest or deceitful.

   a false witness

6. Not faithful or loyal, as to obligations, allegiance, vows, etc.; untrue; treacherous.

   a false friend, lover, or subject;  false to promises

7. Not well founded; not firm or trustworthy; erroneous.

   a false conclusion;  a false construction in grammar

8. Not essential or permanent, as parts of a structure which are temporary or supplemental.
9. Used in the vernacular name of a species (or group of species) together with the name of another species to which it is similar in appearance.

   false killer whale (a dolphin)

10. Out of tune.

noun

A deceiver.