The Vietnamese word for child is
đứa bé

Translations for child and their definitions

con	©
1. n. a child (daughter or son)
con cái - children
con nuôi - an adopted child
gà con - a chick
Con cóc con là con con cóc. - A toadlet is an offspring of a toad.
2. n. (rare, chiefly in translations of ancient texts) a son
3. n. (only in compounds, in fixed expressions) build; stature
4. n. (rare, only in compounds) a small thing
con quay - a spinning top
con lắc - a pendulum
5. pron. I/me (used by children when talking to their parents)
6. pron. (chiefly central Vietnam and southern Vietnam) I/me (used when talking to someone significantly older than the speaker)
7. pron. you (used by parents when talking to their children)
8. pron. (chiefly central Vietnam and southern Vietnam) you (used when talking to some significantly younger than the speaker)
Là con thật! - It's you for real!
9. classifier. (Indicates animals (including humans).)
10. classifier. (disrespectful) (Indicates female people.)
một thằng, hai con - one guy, two girls
11. classifier. Indicates knives, ships, boats, trains and eye pupils.
con dao - a knife
12. classifier. Indicates roads, rivers, streams and waves.
trên con đường đến hạnh phúc - on the road/path to happiness
13. classifier. (somewhat, literary) (Indicates written characters.)
con chữ - a character or letter
14. classifier. (colloquial) (Indicates wheeled vehicles.)
Anh mày có hẳn hai con xe Honda đấy nhớ! - I have two Honda motorbikes!
15. classifier. (colloquial) (Indicates video games and movies.)
Ông chơi con game này chưa? - Have you played this game?