Meaning

• An old person.

• Someone older than someone else (with possessive).

  "He was four years her senior."

• Someone seen as deserving respect or reverence because of their age.

• An elder or presbyter in the early Church.

• Somebody who is higher in rank, dignity, or office.

• A final-year student at a high school or university.

Meaning

• Older; superior

  "senior citizen"

• Higher in rank, dignity, or office.

  "senior member; senior counsel"

• Of or pertaining to a student's final academic year at a high school (twelfth grade) or university.