Learner's definition of FALSE
1 : not real or genuine — used to say that something is not really what it seems to be 2 : not true or accurate especially : deliberately untrue : done or said to fool or deceive someone
a false promise
He registered at the hotel under a false name.
The loan was obtained on/under false pretenses. [=by pretending that a certain condition or circumstance was true]
3 : based on mistaken ideas 4 a : not faithful or loyal b : not sincere
5 : sudden or deceptive in a threatening way