Definition of "Junior" :

noun: the younger of two persons

"She is two years my junior."

noun: a third-year undergraduate

noun: a son who has the same first name as his father

noun: term of address for a disrespectful and annoying male

"Look here, junior, it's none of your business."

adjective: used of the third or next to final year in United States high school or college

"The junior class."

adjective: including or intended for youthful persons

"A junior sports league."

adjective: younger; lower in rank; shorter in length of tenure or service