The Collaborative International Dictionary of English v.0.48:
Presidial \Pre*sid"i*al\, Presidiary \Pre*sid"i*a*ry\, a. [L. praesidialis and praesidiarius, fr. praesidium a presiding over, defense, guard. See Preside.] Of or pertaining to a garrison; having a garrison. [1913 Webster] There are three presidial castles in this city. --Howell. [1913 Webster]