[General] The mucus came out from his nose.

[jasonree123456]

He has a runny nose. He suddenly sneezed and the mucus came out from his nose.

What is the name we called for the fluid buildup in the nose?

 

[MikeNewYork]

"Mucus" works.

 

[tedmc]

It is mucous (BrE) from the nose and phlegm from the mouth.

not a teacher

 

[MikeNewYork]

"Mucous" is an adjective in AmE -- as in "mucous membrane".

 

[tedmc]

Sorry, I got it wrong. It is also mucus in BrE, not mucous.

 

[Rover_KE]

The OP needs to know that informally we call it 'snot' — an unpleasant word that many like to avoid.

 

[MikeNewYork]

Also "boogers", even more unpleasant.