The definition of nifty is slang to describe something that is good or great.
An example of something nifty is how a 50's sitcom character describes a girl he likes.
Informal attractive, smart, stylish, enjoyable, etc.: a generalized term of approval
Origin of niftyorigin, originally theatrical slang, probably ; from magnificent
Slang a nifty person or thing; esp., a clever or witty remark
First-rate; great: a nifty idea.
A nifty person or thing, especially a clever joke.
Origin of niftyOrigin unknown.