The Collaborative International Dictionary of English v.0.48:

Gladius \Gla"di*us\, n.; pl. Gladii. [L., a sword.] (Zool.)
   The internal shell, or pen, of cephalopods like the squids.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

GLADIUS. In our old Latin authors, and in the Norman laws, this word was
used to signify supreme jurisdiction, jus gladii.