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c.1200, "chief household officer, justice of the peace," from Old French conestable (12c., Modern French connétable), "steward, governor," principal officer of the Frankish king's household, from Late Latin comes stabuli, literally "count of the stable" (established by Theodosian Code, c.438 C.E.), hence, "chief groom." See count (n.). Second element is from Latin stabulum "stable, standing place" (see stable (n.)). Probably a translation of a Germanic word. Meaning "an officer of the peace" is from c.1600, transferred to "police officer" 1836. French reborrowed constable 19c. as "English police."
officer of state in western European countries from medieval times and also of certain executive legal officials in Great Britain and the United States. The title comes stabuli is found in the Roman and particularly in the Eastern Roman, or Byzantine, Empire from the 5th century AD as that of the head of the stables at the imperial court. The Franks borrowed the title, and under the Merovingian and Carolingian kings of western Europe the comes stabuli was in charge of the royal stud, with the marshal (marescallus) as his subordinate officer. In the 11th century the constable (connetable) of France became one of the five great officers of state, with limited powers of jurisdiction and with command of the cavalry. The constable's military duties and judicial powers increased until, by the mid-14th century, he held supreme military command of the army. After the treason of the constable Charles de Bourbon (1523), however, the kings distrusted the power of the office, and for many years in the 16th century it was allowed to remain vacant. It was eliminated in 1627, after the death of Francois de Bonne, Duke de Lesdiguieres, but was revived by Napoleon I, who appointed his brother Louis Bonaparte grand constable. It was finally abolished upon the restoration of the Bourbons.