무엇

Depending on the intonation, 머엇 and 뭐 can mean either 'what' or 'something. If the sentence starts with a high pitch and ends with a downward intonation, then it is an interrogative pronoun meaning 'What ... ?' However if the rising intonation comes at the end, it is a indefinite pronoun meaning 'something.' See the examples below

Sentence	Intonation	Audio	Meaning
(need sentence)	Up and then down	(insert audio)
(need sentence)	Gradually rising	(insert audio)

무엇

• 무엇 is usually used in more formal situations and isn't colloquial.
• 무엇이 is 무엇 plus the subject marker 이.
• 무엇을 is 무엇 plus the object marker 을.

뭐

• 뭐 is the contracted version version of 무엇 and is used much more frequently in colloquial speach. It is oftened pronounced as 모 or 머 and also often spelled that way in informal usage, such as text messaging and instant messaging (with friends).
• 뭐가 is 뭐 plus the subject marker 가
• 뭘 is a contraction of 뭐를, which is 뭐 plus the object marker 를.
• 뭐 is sometimes used as a filler for when someone is thinking of what to say.

Sentence examples

As an interrogative pronoun:

Korean	English	Notes
지금 뭐 해요?	What are you doing right now?	뭘 봐?
What are you looking at?

As an indefinite Pronoun

Korean	English	Notes
뭐 하나 물어 봐도 돼요?	Is it ok if I ask you something?

As a filler

Korean	English	Notes