from
The Collaborative International Dictionary of English v.0.48
Senior \Sen"ior\, n.
1. A person who is older than another; one more advanced in
life.
[1913 Webster]
2. One older in office, or whose entrance upon office was
anterior to that of another; one prior in grade.
[1913 Webster]
3. An aged person; an older. --Dryden.
[1913 Webster]
Each village senior paused to scan,
And speak the lovely caravan. --Emerson.
[1913 Webster]
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.
[1913 Webster]