Learn Hardcore Indonesian: Sesi intensif dimulai pukul delapan. - The intensive session starts at eight o’clock.

Yes, intensif comes from the same root as English intensive (via Dutch/European languages). It is common and neutral in tone, used in both spoken and written Indonesian.

You might see it in phrases like:

kursus intensif – intensive course
pelatihan intensif – intensive training

So sesi intensif does not sound strange or overly formal; it is standard Indonesian.

Why is it dimulai and not just mulai? What is the difference?

Both are possible, but they are slightly different grammatically:

mulai = to start (intransitive)
- Sesi intensif mulai pukul delapan.
  The intensive session starts at eight.
memulai = to start something (active transitive)
- Mereka memulai sesi intensif pukul delapan.
  They start the intensive session at eight.
dimulai = is started / is begun (passive)
- Sesi intensif dimulai pukul delapan.
  The intensive session is started at eight.

In everyday use, Sesi intensif mulai pukul delapan and Sesi intensif dimulai pukul delapan are both acceptable. Dimulai sounds slightly more formal and passive, as if someone unstated is starting it.

What does the prefix di- in dimulai indicate?

The prefix di- is the standard passive prefix in Indonesian.

Base verb: mulai – to start
Passive form: di
- mulai → dimulai – is started / is begun

Using di- focuses on the action or the thing affected, not on the doer. In Sesi intensif dimulai pukul delapan, the focus is on the session and when it starts, not on who starts it.

What does pukul mean here, and how is it different from jam?

Both pukul and jam can be used for telling clock time, but there is a nuance:

pukul – more formal, often used in announcements, schedules, invitations
- Rapat dimulai pukul 10. – The meeting starts at 10.
jam – more casual, very common in everyday speech
- Rapat mulai jam 10. – The meeting starts at 10.

In your sentence, pukul delapan means at eight o’clock. You could also say jam delapan, which sounds a bit more conversational.

Why is there no explicit word for at in at eight o’clock?

Indonesian usually uses pukul or jam to play the role of at when talking about clock time.

So:

pukul delapan or jam delapan
literally: strike eight / hour eight
functionally: at eight o’clock

If you want to be more formal, you can add pada:

Sesi intensif dimulai pada pukul delapan.

Here pada is the preposition, but in everyday speech it is often omitted, and pukul or jam alone is enough.

Why is it pukul delapan and not delapan pukul?

Indonesian time expressions follow the pattern:

pukul/jam + number

So you say:

pukul satu – one o’clock
pukul dua – two o’clock
pukul delapan – eight o’clock

Putting the number first (delapan pukul) is not correct for this meaning.

How would I say eight in the morning versus eight at night?

You add a time-of-day word after the number:

pukul delapan pagi – 8 a.m.
pukul delapan malam – 8 p.m.
pukul delapan sore – around 8 in the evening (usually earlier, say 4–6 pm; 8 pm is more often called malam)

So you could say:

Sesi intensif dimulai pukul delapan pagi. – The intensive session starts at 8 a.m.

Without pagi/malam/sore, pukul delapan is context-dependent, but often understood as morning if classes or work are involved.

Is Sesi intensif dimulai pukul delapan formal, or could I use it in casual speech as well?

The sentence is neutral and works in both formal and semi-formal situations, such as:

a course schedule
a teacher telling students
an announcement

In casual everyday speech with friends, you might slightly prefer:

Sesi intensif mulai jam delapan.

That version feels a bit more conversational, but your original sentence is not too formal; it is completely natural.

Where is the subject meaning it or the session? Why is nothing like it written?

In Indonesian, the subject is usually expressed as a noun phrase, and pronouns like it are not used the way English does.

Here, Sesi intensif is the subject of the sentence, so you do not need any extra word for it.

Sesi intensif – subject
dimulai – verb
pukul delapan – time expression

Indonesian does not add a separate pronoun equivalent to it when the subject is already named.

How is tense expressed here? How do I know if it is present, past, or future?

Indonesian verbs do not change form for tense. Dimulai itself is tenseless; the time is understood from context or extra words.

Depending on context, Sesi intensif dimulai pukul delapan could mean:

The intensive session starts at eight (habitual or schedule)
The intensive session will start at eight (future)
The intensive session started at eight (past, if you are telling a story and the time is clear from context)

If you need to be explicit, you add time words:

tadi – earlier / just now
nanti – later
besok – tomorrow

For example: Nanti, sesi intensif dimulai pukul delapan. – Later, the intensive session will start at eight.

Could I drop pukul and just say Sesi intensif dimulai delapan?

In standard Indonesian, you should not drop pukul/jam here. You normally say pukul delapan or jam delapan.

Sesi intensif dimulai pukul delapan. – natural
Sesi intensif dimulai jam delapan. – natural and conversational
Sesi intensif dimulai delapan. – sounds incomplete or ungrammatical in standard Indonesian

In very casual speech some people might omit jam when the context is super clear, but that is not recommended for learners or for clear, standard language.

How do you pronounce the words in this sentence?

Approximate pronunciation (stressed syllables in capitals):

Sesi – SEH-see
intensif – in-TEN-sif (final f is pronounced)
dimulai – dee-moo-LAI (final ai like English eye)
pukul – POO-kool (final l is clear, not dark)
delapan – de-LA-pan

Indonesian stress is usually on the second-to-last syllable, which you can hear in SE-si, in-TEN-sif, di-MU-lai, PU-kul, de-LA-pan.