Ele fingiu dormir.

Because after fingir in this structure, Portuguese uses the infinitive to say what someone pretended to do.

• Ele fingiu dormir = He pretended to sleep
• more naturally in English, often He pretended to be asleep

So dormir stays in its basic form, not dorme or dormia.

In English, we say pretended to sleep, but Portuguese does not need a separate word like to here.

• English: pretended to sleep
• Portuguese: fingiu dormir

This is normal with many Portuguese verbs followed by an infinitive. The infinitive appears on its own.

Fingiu is the pretérito perfeito simples of fingir, third person singular.

That means it refers to a completed action in the past:

• eu fingi = I pretended
• tu fingiste = you pretended
• ele/ela/você fingiu = he/she/you pretended

So Ele fingiu dormir means he did this at some particular moment or in some completed situation in the past.

Both are possible.

Portuguese often drops subject pronouns when the meaning is clear:

• Fingiu dormir.
• Ele fingiu dormir.

Adding ele makes the subject explicit. It can help with clarity, contrast, or emphasis.

For example:

• Ele fingiu dormir, mas ela percebeu.
  He pretended to be asleep, but she noticed.

So ele is not required, but it is perfectly natural.

Yes, that is a very natural way to understand it in English.

Literally, fingiu dormir is pretended to sleep, but in real use it often means:

• He pretended to be asleep
• He pretended he was sleeping

So the idea is usually that he was not really asleep, but acted as if he was.

Yes. Ele fingiu que dormia is also correct.

There is a small difference in structure:

• Ele fingiu dormir = He pretended to sleep / pretended to be asleep
• Ele fingiu que dormia = He pretended that he was sleeping

The version with the infinitive is shorter and very common. The version with que dormia sounds a little more explicit.

Both can exist, but they are not exactly the same.

• fingiu dormir is the simpler and more idiomatic form here
• fingiu estar a dormir means more specifically pretended to be sleeping

In European Portuguese, estar a + infinitive is the usual way to express an ongoing action:

• Ele está a dormir = He is sleeping

So:

• Ele fingiu dormir = He pretended to sleep / be asleep
• Ele fingiu estar a dormir = He pretended to be sleeping

The second one is a bit more explicit about the ongoing state.

A useful approximation is:

• fin-ZHIU

A few points:

• the stress is on -giu
• the gi sounds like the s in measure or the g in genre
• the fin- part has a nasal quality, so it is not exactly like English fin

You do not pronounce it like English finger. The n helps nasalise the vowel.

It is mostly regular in many forms, but it has some spelling/sound changes depending on the tense and person.

For example:

• fingir
• fingiu
• fingi
• finjo

So it is a verb worth memorising rather than treating as completely regular in every form.

Yes. That would change the tense and the meaning slightly.

• Ele fingiu dormir = he pretended to sleep / a completed past action
• Ele fingia dormir = he used to pretend to sleep / he was pretending to sleep

So:

• fingiu = one finished event or a completed action
• fingia = repeated, habitual, ongoing, or background action in the past

Example:

• Quando a mãe entrava no quarto, ele fingia dormir.
  When his mother came into the room, he would pretend to be asleep.

This order is the normal one:

• Ele fingiu dormir.

Portuguese usually puts the main verb first and the infinitive after it in this kind of structure.

You would not normally rearrange it in everyday speech. So for a learner, the safest pattern is:

• subject + fingir + infinitive

For example:

• Ela fingiu ler. = She pretended to read.
• Nós fingimos trabalhar. = We pretended to work.

Yes, very often. This is a productive pattern.

Examples:

• Ela fingiu sorrir. = She pretended to smile.
• Eles fingiram estudar. = They pretended to study.
• Eu fingi não ouvir. = I pretended not to hear.

So once you know fingir + infinitive, you can use it with many other verbs.

In Portuguese, Ele fingiu dormir can cover both ideas, but in English pretended to be asleep is often the most natural translation in context.

That is because the sentence usually describes someone acting as if already asleep, not trying to imitate the process of falling asleep.

So:

• literal: He pretended to sleep
• often more natural: He pretended to be asleep