ordinantia

Ordinantia in medieval Latin means an arranging, an ordering, from ordinare (to put in order, to arrange), from ordo, ordinis (order, row, rank). The word entered English through Old French ordenance in the thirteenth century. The earliest English ordinances were royal decrees — the king ordering things to be done in a specific way. The word gradually migrated from royal to municipal government.

The Ordinance of 1311 in England was a set of regulations imposed on King Edward II by a group of nobles (the Lords Ordainers). The ordinances limited royal power — requiring baronial consent for war, for leaving the realm, and for appointing ministers. This was an early constitutional experiment: using ordinances to restrain the very power that issued them. The ordering was applied to the orderer.

In American law, an ordinance is a law enacted by a city or county government — the most local form of legislation. Traffic regulations, building codes, animal control, noise limits, parking rules — these are ordinances. The word preserved its root meaning perfectly: an ordinance puts things in order at the most immediate level of governance. You encounter ordinances more often than statutes or constitutional provisions.

The word 'ordnance' (military weapons and equipment) is a variant spelling of the same word. The connection is that military supplies were originally items ordered and regulated by the government. The Ordnance Survey (the UK's national mapping agency, founded 1791) was established to produce maps for military use — maps ordered by the Board of Ordnance. Ordering civilians and ordering supplies share a word because both are acts of governmental arrangement.