Из-за опоздания я пропустил начало лекции.

Из-за is a preposition meaning because of or due to. It introduces the cause of what happened.

In this sentence, из-за опоздания means because of the lateness or because I was late.

A useful nuance: из-за often sounds natural when the cause is something undesirable or inconvenient.

Because из-за requires the genitive case.

The base form is опоздание:

• nominative: опоздание
• genitive: опоздания

So:

• из-за опоздания = because of the lateness

This is a very common thing to memorize with prepositions in Russian: many prepositions always require a specific case.

Опоздание is a noun meaning lateness, being late, or delay.

It comes from the verb опоздать, meaning to be late.

So:

• Я опоздал = I was late
• из-за опоздания = because of being late / because of the delay

Russian often leaves out possessive words like my, your, his, etc. when the meaning is already obvious from context.

Here, since the subject is я, it is natural to understand опоздания as my lateness.

You could say:

• Из-за моего опоздания я пропустил начало лекции

But that sounds more explicit. In many contexts, Russian prefers the shorter version.

Пропустил is perfective past, and it fits a single completed event.

The speaker missed a specific thing: the beginning of the lecture. That is a finished result, so perfective is natural.

Compare:

• пропустил = missed, ended up missing
• пропускал = was missing / used to miss / missed repeatedly, depending on context

In this sentence, пропустил is the normal choice.

In the past tense, Russian verbs agree with the subject in gender and number.

So:

• пропустил = masculine singular
• пропустила = feminine singular
• пропустило = neuter singular
• пропустили = plural

That means this sentence sounds as if it is said by a male speaker. A woman would say:

• Из-за опоздания я пропустила начало лекции.

Because начало means beginning, and in Russian you normally say the beginning of something.

So the pattern is:

• начало + genitive

That gives:

• начало лекции = the beginning of the lecture

Here:

• начало is the direct object of пропустил
• лекции is in the genitive because it depends on начало

So literally, this part is structured as missed [the beginning] [of the lecture].

It is accusative singular, because it is the direct object of пропустил.

However, начало is a neuter inanimate noun, so its accusative form looks exactly the same as its nominative form.

So:

• nominative: начало
• accusative: начало

That is why you do not see a visible ending change.

Here пропустить means to miss.

But this verb is broader than the English verb miss. Depending on context, it can also mean things like:

• to skip
• to let through
• to let pass
• to overlook

In this sentence, the meaning is clearly to miss:

• пропустить начало лекции = to miss the beginning of the lecture

Yes. Russian word order is more flexible than English word order.

This sentence begins with Из-за опоздания to highlight the reason first:

• Из-за опоздания я пропустил начало лекции.

You could also say:

• Я пропустил начало лекции из-за опоздания.

Both are grammatical. The original version gives a little more emphasis to the cause.

Yes, often it can.

Russian frequently drops subject pronouns when the verb form already makes the subject clear. So in conversation, you might hear:

• Из-за опоздания пропустил начало лекции.

That still sounds natural, especially if the subject is obvious from context.

Including я is also completely fine. It can make the sentence clearer or slightly more explicit.

The main stresses are:

• из-за́
• опозда́ния
• я
• пропусти́л
• нача́ло
• ле́кции

A rough pronunciation guide:

• из-за́ = iz-ZA
• опозда́ния = a-paz-DA-ni-ya
• пропусти́л = pra-pus-TEEL
• нача́ло = na-CHA-la
• ле́кции = LYEK-tsii

Pay special attention to ле́кции: the stress is on the first syllable.

No. They are different prepositions.

• из usually means from, out of
• из-за is a fixed preposition meaning because of

So in this sentence, you should think of из-за as one unit, not as separate words with their basic literal meanings.

It is best to learn из-за + genitive as a set pattern.