la boca NOUN mouth
You’ll probably already know the basic meaning of boca, which is a person’s or animal’s mouth.
No debes hablar con la boca llena. You shouldn’t talk with your mouth full.
It’s often used in the phrases boca arriba, face up, and boca abajo, face down:
El viejo estaba tumbado boca abajo. The old man was lying face down.
dormir boca arriba to sleep on your back
If something really surprises you, in Spanish you’re left with your mouth open:
La gente se ha quedado con la boca abierta. People were absolutely amazed.
Nos ha dejado a todos con la boca abierta. He completely amazed us all.