Longman Dictionary of Contemporary English - junior

~1 adj 1 only before noun having a low rank in an organization or profession  (a junior doctor)  (- opposite senior2) 2 be junior to sb to have a lower rank than someone  (- see also senior2) ~2 n 1 be two/five/ten etc years sb's junior to be two, five, ten etc years younger than someone  (She married a man seven years her junior.) 2 especially BrE someone who has a low rank in an organization or profession  (an office junior) 3 BrE a pupil in a junior school 4 AmE a student in the year before the final year of high school or university  (- compare freshman, senior1 (2), sophomore) 5 AmE especially humorous a way of speaking to or about your son  (What are we going to do about junior if we go out tonight?)  (- see also senior1)