Learn Hardcore Malay: Kenapa awak tak makan tengahari tadi?

kenapa is more informal and very common in everyday speech, especially in Malaysia.
mengapa is a bit more formal or neutral, often seen in writing, news, or more polite speech.

In this sentence, Kenapa awak tak makan tengahari tadi? sounds natural and conversational. A slightly more formal version would be Mengapa awak tidak makan tengah hari tadi?

Why is there no word for did or didn't in the Malay sentence?

Malay does not use auxiliary verbs like do/did to form questions or negatives.

English: Why didn't you eat lunch?
Malay: Kenapa awak tak makan tengahari tadi?

The past time is shown by the time word tadi (earlier / just now), not by changing the verb or adding something like did. The negative tak simply means not / don't / didn't, depending on context and time markers.

How is past tense shown in this sentence if the verb makan doesn’t change?

Malay verbs do not change for tense. Instead, time words are used.

In this sentence, tadi indicates that the action happened earlier (earlier today / just now):

makan = to eat (no tense by itself)
tadi = earlier / just now (earlier today)
Together with context: tak makan … tadi = didn't eat … earlier

If you wanted, you could also add sudah (already) in other sentences, but here tadi is enough to show it is in the past.

What is the difference between tak and tidak? Which one is correct here?

Both tak and tidak mean not.

tak is the informal/shortened form, very common in everyday spoken Malay.
tidak is the full form, more formal or careful speech, also standard in writing.

In this sentence:

Informal: Kenapa awak tak makan tengahari tadi?
More formal: Mengapa awak tidak makan tengah hari tadi?

Both are grammatically correct; the choice mainly affects the level of formality and the “spoken vs written” feel.

Is awak formal, informal, or rude? How does it compare with kamu, anda, or kau?

awak is generally neutral and friendly in Malaysia. It is appropriate:

between friends
between people of similar age
in many everyday situations

Comparison:

awak – neutral, everyday, safe in many contexts.
kamu – can feel a bit distant, or textbook-y in Malaysia; more natural in some regions and in Indonesian.
anda – polite, formal, often used in customer-facing speech, advertisements, public announcements.
kau / engkau – very informal; can be intimate among close friends, but can also sound rude or abrupt if used with the wrong person.

So, Kenapa awak tak makan tengahari tadi? sounds like a normal, friendly question.

Can I omit awak and just say Kenapa tak makan tengahari tadi? Is that still correct?

Yes, that is correct and very natural.

Malay often drops the subject pronoun when it is clear from context. So:

Kenapa awak tak makan tengahari tadi?
Kenapa tak makan tengahari tadi?

Both can mean the same thing, depending on who you are talking to and the situation. The second one feels a bit more casual and relies on context to show that you are the subject.

Does makan tengahari literally mean “eat afternoon,” or is it a fixed expression meaning “eat lunch”?

Literally:

makan = to eat
tengah hari / tengahari = midday / noon

So makan tengah hari literally is eat at midday, but functionally it means eat lunch.

It is commonly used to mean having lunch:

Saya belum makan tengah hari. = I haven’t had lunch yet.
Jom makan tengahari. = Let’s have lunch.

In writing, you will often see tengah hari (two words). In everyday writing and speech, tengahari (one word) also appears, especially informally.

What is the difference between tengahari and petang? Why use tengahari here?

They refer to different times of day:

tengah hari / tengahari = around midday, roughly 12–2 pm.
petang = afternoon / early evening, roughly 3–6 pm (varies by context/region).

Lunch is naturally linked with tengah hari, not petang, so:

makan tengah hari = have lunch
petang would more likely be used in phrases about doing things in the afternoon, e.g. jalan-jalan petang (afternoon walk), not specifically lunch.

What exactly does tadi mean? Is it “earlier,” “just now,” or “this afternoon”?

tadi means earlier (today) or a short while ago, depending on context. It usually refers to something that happened earlier on the same day.

It does not itself mean “afternoon” or “this afternoon”; it just marks an earlier time today.

Examples:

Saya nampak dia tadi. = I saw him/her earlier (today).
Tadi awak di mana? = Where were you just now / earlier?

In Kenapa awak tak makan tengahari tadi?, tadi tells us that the not eating lunch happened earlier (today), not right now and not on some other day.

Could I move tadi to another position, like Kenapa tadi awak tak makan tengahari? Is that still correct?

Yes, tadi can move around, and the sentence can still be correct. Common options:

Kenapa awak tak makan tengahari tadi?
Kenapa tadi awak tak makan tengahari?
Tadi, kenapa awak tak makan tengahari?

All are understandable and acceptable. The differences are subtle:

Version 1 is the most straightforward and common.
Version 2 and 3 give a little more emphasis to tadi (“earlier, why didn’t you…?”) but are still natural.

If I want to be more polite or formal, how could I rephrase this sentence?

To sound more polite/formal, you can:

Use mengapa instead of kenapa.
Use tidak instead of tak.
Use anda instead of awak (especially in customer service or official contexts).
Separate tengah hari in writing.

For example:

Mengapa anda tidak makan tengah hari tadi?

This sounds polite and suitable for formal situations, written language, or speaking to someone you don’t know well (customer, audience, etc.).

How would I change this sentence to talk about breakfast or dinner instead of lunch?

You mainly replace tengahari / tengah hari with the appropriate meal word:

sarapan = breakfast
makan pagi = breakfast (literally “eat morning”)
makan malam = dinner / supper

Examples:

Kenapa awak tak sarapan tadi? = Why didn’t you eat breakfast earlier?
Kenapa awak tak makan pagi tadi? = Why didn’t you have breakfast earlier?
Kenapa awak tak makan malam tadi? = Why didn’t you have dinner last night / earlier in the evening?

Note: tadi by itself usually means earlier today, but in practice malam tadi is commonly understood as “last night” (the most recent night).