Constable is a title used in police organizations.
History and specifics
In the early 24th century, constable was a rank inside the Bajoran Militia's City Watch. Both Darrah Mace and Proka Migdal held the rank while stationed in Korto. (TLE - Terok Nor novel: Day of the Vipers)
Because of its connotations of old-style police work, constable was used as an affectionate nickname for Security Chief Odo on Cardassian space station Terok Nor, and was carried over by his new compatriots when the station became Deep Space 9. The nickname was originally given to him in the year 2365 by Bajoran freedom fighter, Kira Nerys. (DS9 episode: "Necessary Evil")