(US, law) The power of a court to review and potentially modify the decisions made by another court or tribunal.

plural of appellate court

(law) A court having jurisdiction to hear appeals and review a lower court's decisions.

(mathematics) Any polynomial sequence p_n(x)_(n=0,1,2,…) satisfying the identity d/(dx)p_n(x)=np_n-1(x), and in which p_0(x) is a non-zero constant.

plural of Appell sequence