older person
1 a person who is older than somebody elseShe was ten years his senior.My brother is my senior by two years. compare junior2 (especially North American English) = senior citizen higher rank
3 a person who is higher in rank or statusShe felt unappreciated both by her colleagues and her seniors.
in sport
4 adults or people who have reached an advanced leveltennis coaching for juniors and seniors in school/college
5 (British English) a child at a senior school; an older child in a school6 (in the US and some other countries) a student in the last year at a high school or collegehigh school seniors compare sophomore 
ˈsiːniə(r) 
ˈsiːniər 