Ob-sĭd’ĭ-o-nal, a.

a. [Lat. obsidionalis, from obsidio, a siege, from obsidere, to besiege; Fr. & Sp. obsidional, It. ossidionale. See OBSESS.] Pertaining to a siege.

Obsidional crown, a crown bestowed upon a general who raised the siege of a beleaguered place.

We shall hardly gain the obsidional crown, which, you are well aware, was made of the roots or grain which takes root within the place besieged. W. Scott.