ablative : Idioms & Phrases

• noun a constituent in Latin grammar; a noun and its modifier can function as a sentence modifier
  

WordNet

• a construction in Latin, in which a noun in the ablative case has a participle (either expressed or implied), agreeing with it in gender, number, and case, both words forming a clause by themselves and being unconnected, grammatically, with the rest of the sentence; as, Tarquinio regnante, Pythagoras venit, i. e., Tarquinius reigning, Pythagoras came.

Webster 1913

• noun the case indicating the agent in passive sentences or the instrument or manner or place of the action described by the verb
  ablative.
  

WordNet

• in full court, or with full judicial authority; as, sittings in banc (distinguished from sittings at nisi prius).

Webster 1913