Seniority means having been in a position, organization, or job longer than others. A teacher with 20 years of experience has more seniority than one who just started this year. In Congress, senators with more years of service have greater seniority than newer senators.

Seniority often brings certain advantages or privileges. At many companies, workers with more seniority might get first choice of vacation days or better parking spots. In some workplaces, when promotions or layoffs happen, seniority plays a role in deciding who moves up or who stays. A senior employee is someone with high seniority.

While seniority is based on time rather than age, the two can go together. Your older sister has seniority in your family simply because she was born first.

Seniority systems reward loyalty and experience, but they can also frustrate talented newcomers who must wait their turn. A brilliant young scientist might have great ideas but little seniority in her research lab.