adjective / noun
senior
SEE-nee-er/ˈsiːniər/
More advanced in age or standing.
The senior worker guides the younger team members at the workbench.

Etymology
The pieces mean “older,” and English first used senior to distinguish a father from a same-named son. The comparison later extended to longer service and higher rank.
In context
By 1813, Napoleon relied on Macdonald as one of his senior Marshals.
someone who's targeting senior citizens,
More examples
- A senior engineer supervises the new employees.
- My sister is three years my senior.
- High school seniors graduate at the end of this semester.
Forms
senior · seniors · more senior · most senior
seniority noun — Higher standing based on length of service.