Source : Webster's Revised Unabridged Dictionary (1913)

Quadra \Quad"ra\, n.; pl. {Quadr[ae]}. [L., a square, the socle,
   a platband, a fillet.] (Arch.)
   (a) The plinth, or lowest member, of any pedestal, podium,
       water table, or the like.
   (b) A fillet, or listel.