seniority /sē-ni-orˈi-ti/ noun

1. The state or fact of being senior
2. Priority by age, time of service, or standing
3. A body of seniors or senior fellows

senior citizen noun

An old-age pensioner

senior common room or (Cambridge University) senior combination room noun

In some universities, a common room for the use of staff (cf junior common room, middle common room; abbrev SCR)

senior moment noun (informal)

A momentary lapse in memory, esp experienced by an older person

senior optime see optime

senior service noun

The Royal Navy