Learn Hardcore Indonesian: Dia memakai baju biru di pesta tadi malam. - He/She wore a blue shirt at the party last night.

Neutral/descriptive: dia laki-laki (male), dia perempuan (female), pria itu, wanita itu.
Casual: cowok itu, cewek itu.
Respectful for elders/important people: beliau. Note: ia is a more formal/written variant of dia (mostly as a subject). You’d say Ia memakai… but usually not use ia after prepositions; there you use dia or the clitic -nya (e.g., kepadanya).

Is memakai the same as pakai or mengenakan? Which sounds most natural for clothing?

pakai: very common in everyday speech. Example: Dia pakai baju biru…
memakai: a bit more neutral/formal than plain pakai. Your sentence is perfectly natural.
mengenakan: more formal/literary/news style, often used specifically for clothing. Example: Dia mengenakan baju biru…
Avoid menggunakan for clothes; it means “to use” and sounds odd with garments.

Why is it memakai and not “mengpakai”? What happened to the “p”?

It’s the meN- prefix rule. The base verb is pakai. When you add meN-, certain initial consonants change:

p → drop p, use mem-: mem
- (p)akai → memakai
t → drop t, use men-: menulis (from tulis)
k → drop k, use meng-: mengambil (from ambil), mengantar (from antar)
s → drop s, use meny-: menyapu (from sapu)

Does baju mean “shirt” or “clothes”? What if I mean a dress or T‑shirt?

baju can mean “clothes” in general or “a top/shirt” depending on context. If you want to be specific:

kemeja = dress shirt (with buttons/collar)
kaus/kaos = T‑shirt
gaun = dress
rok = skirt
pakaian = clothing (more general/uncountable) So you could say Dia memakai kemeja biru… if you mean a dress shirt.

Why is it baju biru and not “biru baju”? Where do adjectives go?

In Indonesian, adjectives usually follow the noun: baju biru (blue shirt). With multiple adjectives: noun + adj + adj, e.g., baju biru tua (dark blue shirt). You can also use yang to clarify: baju yang biru (“the one that is blue”), or baju yang sangat biru for emphasis.

Can I say di pesta or must it be pada pesta? And what’s the difference with ke pesta?

di pesta = at the party (location). This is the most natural here.
pada pesta = at the party, but quite formal/literary.
ke pesta = to the party (movement/direction), not correct for “at.”

Do I write di pesta or dipesta?

As a preposition meaning “at/in,” di is written separately: di pesta. The attached form di- is a prefix for passive verbs (e.g., dipakai), not for locations.

Is tadi malam the only way to say “last night”? What about malam tadi, kemarin malam, and semalam?

tadi malam = last night (most common).
malam tadi = same meaning; just reversed order, also fine.
kemarin malam or malam kemarin = also “last night” (regional/variant preference).
semalam = often “last night,” but can also mean “for one night.” For “all night long,” use semalaman to avoid ambiguity.

How does past tense work here? Why isn’t the verb marked for past?

Indonesian verbs don’t inflect for tense. Time words like tadi malam provide the past meaning. You can add aspect:

sudah/telah (already): Dia sudah memakai…
For ongoing action at a past time you usually rely on context or time phrases rather than verb changes.

Can I move the time/place around, like starting with Tadi malam or Di pesta?

Yes, Indonesian allows fronting for emphasis or flow:

Tadi malam dia memakai baju biru di pesta.
Di pesta tadi malam, dia memakai baju biru.
Dia memakai baju biru di pesta tadi malam. (your version) All are acceptable.

Can I drop Dia and just say Memakai baju biru di pesta tadi malam?

In casual conversation, subjects are often dropped when context is clear, especially as short answers:

Q: Dia pakai apa semalam? A: Baju biru.
As a full standalone sentence, keep Dia for clarity and completeness.

If I want to say “at the party” with a definite “the,” how do I mark that? Is di pesta definite?

Indonesian doesn’t have articles. di pesta can be “at a/the party” depending on context. To make it clearly definite, add itu or specify:

di pesta itu tadi malam (at that party last night)
di pesta ulang tahunnya (at his/her birthday party)

How do I say “his/her blue shirt” instead of just “a blue shirt”?

Use -nya for possession/definiteness:

Dia memakai baju birunya di pesta tadi malam. = He/She wore his/her blue shirt. You can also say bajunya yang biru (“the one that’s blue”) for contrastive meaning.

How do I express “was wearing” (ongoing through the party) vs “put on” (the act of dressing)?

General “was wearing” (state during the event): Dia mengenakan baju biru saat/selama pesta.
Completed “put on” (the act): Dia mengenakan/memakai baju biru tadi malam (context can imply the moment of putting it on).
sedang marks an action in progress at a time; with clothing it often implies the act of putting it on: Dia sedang memakai baju = he/she is in the middle of putting on clothes.

Is the sentence formal, neutral, or casual? Any common casual alternatives?

It’s neutral. Casual speech often uses pakai and sometimes semalam:

Dia pakai baju biru di pesta semalam. In chatty Jakarta style, you may even see pake (colloquial spelling of pakai).

Could I make a passive version, like “The blue shirt was worn by him/her”?

Yes:

Baju biru itu dipakai dia di pesta tadi malam.
More formal: Baju biru tersebut dikenakan olehnya di pesta tadi malam. Here di- is the passive verb prefix.

Is pesta always “party”? Are there other options?

pesta = party. Related words:

acara = event/function (broad)
perayaan = celebration
resepsi = reception (e.g., wedding) You can specify: pesta ulang tahun, pesta pernikahan, pesta kantor, etc.

Any quick pronunciation tips for the words in this sentence?

dia = dee-ah (two syllables)
memakai = mə-mah-kai (final ai like English “eye”)
baju = bah-joo
biru = bee-roo
di = dee
pesta = peh-stah
tadi = tah-dee
malam = mah-lahm