Webster's Revised Unabridged Dictionary · 1913

Senior

Senior , adjective

[Latin senior, compar. of senex, gen. senis, old. See Sir.]

1.
More advanced than another in age; prior in age; elder; hence, more advanced in dignity, rank, or office; superior; as, senior member; senior counsel.
2.
Belonging to the final year of the regular course in American colleges, or in professional schools.

Senior , noun

1.
A person who is older than another; one more advanced in life.
2.
One older in office, or whose entrance upon office was anterior to that of another; one prior in grade.
3.
An aged person; an older. — Dryden
Each village senior paused to scan, And speak the lovely caravan. — Emerson
4.
One in the fourth or final year of his collegiate course at an American college; -- originally called senior sophister; also, one in the last year of the course at a professional schools or at a seminary.