Definition from Wiktionary, the free dictionary
Alternative forms 
- (mathematics) Of a real number, either positive or zero; not negative; greater than or equal to zero.
- Distances are non-negative.
- (mathematics) Of a real valued function, functional, etc. which has non-negative values over a particular domain D.
- For all ,
Usage notes 
Can be used for an element of a subset of the real numbers, eg rationals or integers. This term is not the same as positive.