appellant

adj

1. (not-comparable)Of or relating to appeals; appellate.

   “appellant jurisdiction.”

2. (not-comparable)In the process of appealing.

   “Firſt, heauen be the record to my ſpeech, In the deuotion of a ſubiects loue, Tendering the precious ſafetie of my Prince, And free from other misbegotten hate, Come I appealant to rhis [sic] Princely preſence.”

noun

1. A litigant or party that is making an appeal in court.

   “The appellant made her submissions to the court.”

2. One who makes an earnest entreaty of any kind.
3. (obsolete)One who challenges another to single combat.
4. (historical)One of the clergy in the Jansenist controversy who rejected the bull Unigenitus issued in 1713, appealing to a pope "better informed", or to a general council.