Page "Zero-based numbering" Paragraph 0

Zero-based numbering is numbering in which the initial element of a sequence is assigned the index 0, rather than the index 1 as is typical in everyday circumstances.

Under zero-based numbering, the initial element is sometimes termed the zeroth element, rather than the first element ; zeroth is a coined ordinal number corresponding to the number zero.

In some cases, an object or value that does not ( originally ) belong to a given sequence, but which could be naturally placed before its initial element, may be termed the zeroth element.

There is not wide agreement regarding the correctness of using zero as an ordinal ( nor regarding use of the term zeroth ) as it creates ambiguity for all subsequent elements of the sequence when lacking context.