Menino vs. garoto vs. rapaz vs. moço vs. miúdo
Portuguese offers a rich variety of words to say "boy", with the choice depending largely on the age of the person, the level of formality, and the region (Brazil versus Portugal). While menino is the standard term, words like garoto, rapaz, moço, and miúdo add specific nuances regarding maturity and geography.
Menino
A1This is the most standard, neutral, and universal word for a male child. It can be used from infancy up until the early teenage years. Menino generally focuses on the innocence or childhood status of the boy.
O menino está brincando no parque.
(The boy is playing in the park.)
Seja um bom menino e coma seus vegetais.
(Be a good boy and eat your vegetables.)
A mãe segurou a mão do menino para atravessar a rua.
(The mother held the boy's hand to cross the street.)
Garoto
A2This term is very common in Brazil and is slightly more informal than menino. It translates closely to "kid" or "lad". Garoto is often used for school-aged boys and teenagers, implying a bit more energy or personality than the neutral menino.
Aquele garoto joga futebol muito bem.
(That kid plays soccer very well.)
Ei garoto, você deixou cair seu boné.
(Hey kid, you dropped your cap.)
Ele é um garoto de ouro.
(He is a golden boy.)
Rapaz
A2This word describes an older boy, usually a teenager or a young adult. It is equivalent to "young man" or "guy." Rapaz indicates that the boy is no longer a child and is approaching adulthood. It can also be used as a vocative to address a group of men.
Ele já é um rapaz alto e forte.
(He is already a tall and strong young man.)
O rapaz da entrega chegou com a pizza.
(The delivery guy arrived with the pizza.)
Vamos logo, rapazes!
(Let's go, guys!)
Moço
A2This usually refers to a young adult. It is often used as a polite way to address a young male stranger, similar to saying "young man" or a youthful version of "sir", Moço implies youth but with a level of respect.
Com licença, moço, você sabe onde fica o banco?
(Excuse me, young man, do you know where the bank is?)
Ela está namorando um moço muito educado.
(She is dating a very polite young man.)
O moço que me atendeu foi muito gentil.
(The young man who served me was very kind.)
Miúdo
B1This word is used primarily in European Portuguese (Portugal) to mean "kid", "boy", or "little one". In Brazil, miúdo is an adjective usually meaning tiny or small, but in Portugal, it is the standard noun for a child.
Os miúdos estão a jogar à bola na rua.
(The kids are playing ball in the street.)
Este miúdo não pára quieto um segundo.
(This kid doesn't stay still for a second.)
Quando eu era miúdo, gostava muito de ler.
(When I was a kid, I liked reading very much.)
Summary
To select the right word, consider the age and location. Use menino as the safest general term for a child. Use garoto for a casual feel in Brazil (like "kid"). Switch to rapaz or moço when the boy becomes a teenager or young adult. Finally, use miúdo if you are in Portugal and referring to a child.