Definition from Wiktionary, the free dictionary
- (mathematics) a member of the set of natural numbers — a positive integer (set of [1,2,3,...])
- (mathematics) a member of the set of natural numbers — a non-negative integer (set of [0,1,2,3,...]).
2007, Mark Bridger, REAL ANALYSIS: A Constructive Approach, Hoboken, New Jersey: John Wiley & Sons, page 3:
- A careful derivation of the arithmetic properties of the natural numbers , using induction, was done by G. Peano (1858–1932). It is a lot of fun, but we will not pursue any of it here.