adj. & n.
--adj.
1. (often foll. by to) more or most advanced in age or standing.
2 of high or highest position.
3 (placed after a person's name) senior to another of the same name.
4 (of a school) having pupils in an older age-range (esp. over 11).
5 US of the final year at a university, high school, etc.
--n.
1. a person of advanced age or comparatively long service etc.
2 one's elder, or one's superior in length of service, membership, etc. (is my senior).
3 a senior student.
Phrases and idioms:
senior citizen an elderly person, esp. an old-age pensioner. senior college US a college in which the last two years' work for a bachelor's degree is done. senior common (or combination) room Brit. a room for use by senior members of a college. senior nursing officer the person in charge of nursing services in a hospital. senior officer an officer to whom a junior is responsible. senior partner the head of a firm. senior service Brit. the Royal Navy as opposed to the Army. senior tutor Brit. a college tutor in charge of the teaching arrangements.
Derivatives:
seniority n.
Etymology: ME f. L, older, older man, compar. of senex senis old man, old