Lord; a lord. Also the elder. An addition to the name of the elder of two persons having the same name. Senior counsel. Of two or more counsel retained on the same side of a cause, ‘he is the “senior” who is the elder, or more important in rank or estimation, or who is charged with the more difficult or important parts of the management of the case. Senior judge. Of several judges composing a court, the “senior” judge is the one who holds the oldest commission, or who has served the longest time under his present commission.
SENIOR
TheLaw.com Law Dictionary & Black's Law Dictionary 2nd Ed.