A law, a statute, a decree.
An ordinance is a law enacted by a municipal body, such as a city council or county commission (sometimes called county council or county board of supervisors). Ordinances govern matters not already covered by state or federal laws such as zoning, safety and building regulations.
This word is more usually applied to the laws of a corporation than to the acts of the legislature; as the ordinances of the city of Philadelphia.
Where the proceeding consisted only of a petition from parliament and an answer from the king, these were entered on the parliament roll; and if the matter was of a public nature, the whole was then styled an ordinance; if, however, the petition and answer were not only of a public but a novel nature, they were then formed into an act by the king with the aid of his council and judges and entered on the statute roll." According to Lord Coke, the difference between a statute and an ordinance is, that the latter has not had the assent of the king, lords, and commons, but is made merely by two of those powers.