Der Lkw wartet draußen.

Lkw is a masculine noun in German, so its basic dictionary form takes der.

In this sentence, der Lkw is the subject of the verb wartet, so it is in the nominative case:

• der Lkw = the truck / lorry

You would see other forms in other cases, for example:

• Ich sehe den Lkw. = I see the truck.
  Here den Lkw is accusative.

So in Der Lkw wartet draußen, der is used because the truck is the one doing the waiting.

Lkw is the common abbreviation for Lastkraftwagen, which literally means something like load-power-vehicle and corresponds to truck or lorry.

A few useful points:

• der Lkw = the truck / lorry
• plural: die Lkw
  The abbreviation usually stays the same in the plural.

In everyday German, Lkw is much more common than the full word Lastkraftwagen.

German speakers usually pronounce the letters separately:

• L = el
• k = ka
• w = veh

So Lkw is said roughly like el-ka-veh.

That is very important for English speakers, because German w is pronounced like English v, not like English w.

The infinitive is warten = to wait.

Here it is conjugated for er/sie/es because der Lkw is a singular third-person subject:

• ich warte
• du wartest
• er/sie/es wartet
• wir warten
• ihr wartet
• sie/Sie warten

Since der Lkw is grammatically like er, the correct form is wartet.

Sometimes yes, sometimes no.

In Der Lkw wartet draußen, warten is used without an object. It simply means is waiting.

But if you say wait for someone/something, German usually uses auf:

• Der Lkw wartet auf den Fahrer. = The truck is waiting for the driver.

So:

• warten = to wait
• auf jemanden / etwas warten = to wait for someone / something

That is a very common difference from English.

draußen means outside or outdoors.

In this sentence, it tells you where the truck is waiting:

• Der Lkw wartet draußen. = The truck is waiting outside.

It is an adverb, not an adjective. That means it modifies the whole action rather than describing a noun directly.

Compare:

• Der Lkw wartet draußen. = The truck is waiting outside.
• der draußen wartende Lkw = the truck waiting outside

German often puts information about time, manner, and place later in the sentence, especially after the verb in a simple statement.

The basic structure here is:

• Der Lkw = subject
• wartet = verb
• draußen = adverb of place

So this word order is very natural:

• Der Lkw wartet draußen.

You can move elements around for emphasis, but the verb still has to stay in the second position in a main clause:

• Draußen wartet der Lkw.
  This emphasizes outside.

Both are correct, but the original sentence is the most neutral.

Yes, there is a difference.

• draußen usually means outside / outdoors
• außen usually means on the outside / exterior

Examples:

• Der Lkw wartet draußen. = The truck is waiting outside.
• Der Lkw ist außen schmutzig. = The truck is dirty on the outside.

So in your sentence, draußen is the natural choice because it refers to location in the sense of being outside.

Yes. In standard German, all nouns are capitalized.

So:

• der Lkw
• der Fahrer
• das Haus

That is why Lkw is capitalized even in the middle of the sentence.

Other words in this sentence are not nouns:

• wartet = verb
• draußen = adverb

So they are not capitalized unless they begin the sentence.

Yes. Depending on region and style, you may also hear other words, such as:

• der Lastwagen
• sometimes der Laster in informal use

But der Lkw is extremely common and standard.

So for learners, Lkw is a very useful everyday word to know.