Learn Hardcore German: Was meinst du?

In Was meinst du?, was functions as the direct object of the transitive verb meinen, so it is in the accusative case. However, since was has the same form in both nominative and accusative, it remains was.

Why is the verb meinst in the second position, before the subject du?

German main clauses with a question word follow the V2 (verb-second) rule: the question word (was) is first, the conjugated verb (meinst) must come second, and the subject (du) follows.

What’s the difference between Was meinst du? and Was denkst du?

Both can be used to ask for someone's thoughts, but:

Was meinst du? focuses on opinion or meaning (“What do you think/opine?” or “What do you mean?”).
Was denkst du? emphasizes the thinking process or belief (“What do you think/consider?”).
Often they overlap, but if you want to stress “opinion” use meinen. You can also add dazu for “about it”: Was meinst du dazu? / Was denkst du dazu?.

How would I ask Was meinst du? in a formal or plural situation?

Formal singular or plural Sie: Was meinen Sie?
Informal plural ihr: Was meint ihr?

Why must I include the subject pronoun du? In English we can sometimes omit it.

German is a non-pro-drop language, so you always need to include the subject pronoun in main clauses. You cannot say Was meinst?; you must say Was meinst du?.

What’s the difference between Was meinst du? and Wie meinst du das?

Was meinst du? can mean “What do you mean?” (asking for clarification) or “What is your opinion?” (depending on context).
Wie meinst du das? specifically means “How do you mean that?”—you’re asking the person to explain how they meant something, not what they think about it.

Is it possible to invert the order and say Meinst du was?, and would it change the meaning?

While Meinst du was? is grammatically acceptable, it’s not used to ask for opinion or clarification. It might sound like you’re asking “Do you intend something?” rather than “What do you mean/think?”. Stick with Was meinst du? for that meaning.

How do I pronounce Was meinst du? correctly?

Was: /vas/ (W sounds like English V)
meinst: /maɪnst/ (EU pronounced like “oy” in “boy”)
du: /duː/ (long U, like “oo” in “food”)
Overall IPA: [vas maɪnst duː], with a slightly rising intonation at the end for a question.