Dia kehilangan satu anting di pesta tadi malam.

Dia can mean either he or she. Indonesian third-person singular pronouns usually do not show gender. You figure it out from context.

A learner should also know:

• dia is common in speech and everyday writing
• ia also means he/she, but sounds more formal and is more common in writing

So in this sentence, dia simply means he/she.

Because kehilangan means to lose, while hilang means to be lost or to disappear.

Compare:

• Dia kehilangan satu anting. = He/She lost one earring.
• Satu antingnya hilang. = One of his/her earrings is lost / disappeared.

So:

• kehilangan focuses on the person experiencing the loss
• hilang focuses on the missing thing itself

In this word, ke-...-an forms a verb meaning something like to suffer the loss of or to be deprived of.

Root:

• hilang = lost, gone, disappear

Derived form:

• kehilangan = lose, be missing, suffer the loss of

This pattern is common in Indonesian. It often gives the idea that someone is affected by a state or event.

Satu means one, and here it matters because earrings normally come in pairs. The sentence is emphasizing that only one earring was lost.

Without satu, Dia kehilangan anting sounds less specific. It could suggest earrings in a more general sense, depending on context.

So satu is not just filler here—it highlights the number.

Yes, sebuah anting is possible, but satu anting is very natural here.

Why?

• satu directly emphasizes one
• that emphasis is useful because losing one earring out of a pair is the important point

Also, Indonesian classifiers like buah are often optional in everyday speech, especially when the meaning is already clear.

So:

• satu anting = very natural
• sebuah anting = possible, but a little less direct in this context

That is a very good question. Many learners see anting-anting in dictionaries, and that is indeed a standard word for earring(s).

However, in everyday usage, speakers often shorten it to anting, especially when the number is clear, as in:

• satu anting
• dua anting

So in this sentence, anting sounds natural.

Also, this is a useful reminder that reduplication in Indonesian does not always mean simple plural. Sometimes the reduplicated form is just the dictionary form of the noun.

Here, di is a preposition meaning at or in.

• di pesta = at the party

It is not the passive prefix di-.

A very important spelling rule:

• di as a preposition is written separately: di pesta, di rumah, di sekolah
• di- as a passive prefix is written attached to the verb: diambil, dibeli, dilihat

So the spacing tells you what it is.

Because Indonesian does not have an article system like English a/an/the.

So pesta can mean:

• a party
• the party
• just party in a general sense

The exact meaning comes from context.

In this sentence, di pesta is naturally understood as at the party or at a party, depending on the situation.

Tadi malam is a very common way to say last night.

Even though tadi often means earlier today / earlier just now, the expression tadi malam conventionally means last night.

So:

• tadi pagi = earlier this morning
• tadi siang = earlier today / this afternoon
• tadi malam = last night

It is an everyday, natural expression.

Indonesian verbs do not change form for tense the way English verbs do.

So kehilangan itself does not mean specifically:

• lose
• lost
• will lose

The time is understood from context or time words. Here, tadi malam tells you the event happened in the past.

That means the same verb form could appear in different time frames:

• Dia kehilangan satu anting tadi malam. = past
• Dia kehilangan satu anting sekarang. = present situation
• Dia bisa kehilangan satu anting nanti. = future possibility

Because possession is often left unstated in Indonesian when it is obvious from context.

In this sentence, it is natural to understand that the earring belonged to dia, so Indonesian does not need to say it explicitly.

If you want to make the possession clearer, you could say:

• Dia kehilangan satu antingnya di pesta tadi malam.

That means something like He/She lost one of his/her earrings last night at the party.

So:

• satu anting = natural and simple
• satu antingnya = more explicit about ownership

Not in standard Indonesian if you mean He/She lost one earring.

Why not? Because hilang usually describes the thing that is missing, not the person who lost it.

Better options:

• Dia kehilangan satu anting di pesta tadi malam.
• Satu antingnya hilang di pesta tadi malam.

These are different in focus:

• Dia kehilangan... = focuses on the person who suffered the loss
• Satu antingnya hilang... = focuses on the missing earring

The sentence uses a very common Indonesian order:

Subject + Verb + Object + Place + Time

• Dia = subject
• kehilangan = verb
• satu anting = object
• di pesta = place
• tadi malam = time

This order is natural, but Indonesian is fairly flexible. For example, you could also say:

• Tadi malam, dia kehilangan satu anting di pesta.

That version puts more emphasis on the time. Both are natural.