junior:
(plural: ‘juniors‘; the opposite word in meaning: ‘senior’; for the right pronunciation of this word, please click here)

juniors
a younger person,
e.g.
Don’t be harsh with him; he is just a junior.
a person younger than the speaker (of less age),
e.g.
My cousin is five years my junior. (i.e, my cousin is five years younger than I am.)
a person of a lower rank or position,
e.g.
The seniors must guide the juniors in doing their job properly.

the Martin Luther Kings!
(Often written with a capital ‘J’; shortened form: ‘Jr‘) the son of a man who is given the same name or who is referred to as using the name of the father; (in American English) a reference to a man’s eldest son,
e.g.
(a visitor asking the son about his father) “Is your father in, junior?”
Martin Luther King, Jr. was a renowned American human rights activist.
an informal word of address for rude and annoying person,
e.g.
“Back off, junior! You don’t know who you’re dealing with.”
