The numero sign or numero symbol, № (also represented as Nº, No, or No.) is a typographic abbreviation of the word number indicating ordinal numeration, especially in names and titles.
The Oxford English Dictionary derives the numero sign from Latin numero, the ablative form of numerus ("number", with the ablative denotations of: "to the number, by the number, with the number"). In Romance languages, the numero sign is understood as an abbreviation of the word for "number", e.g. Italian numero, French numéro, and Spanish, Portuguese and Galician número