הכלב מכשכש בזנב.

In Modern Hebrew, present-tense action sentences usually do not use a separate word for is/am/are. The word מכשכש already serves as the present-tense verb.

So הכלב מכשכש בזנב can mean either:

• The dog wags its tail
• The dog is wagging its tail

The exact meaning depends on context.

The prefix ה־ is the Hebrew definite article, meaning the.

So:

• כלב = dog / a dog
• הכלב = the dog

This is very common in Hebrew: instead of a separate word like English the, Hebrew usually adds ה־ to the beginning of the noun.

מכשכש is the masculine singular present-tense form of the verb לכשכש.

Its dictionary form is לכשכש, meaning to wag, to swish, or to shake back and forth in this context.

A useful way to think of it is:

• לכשכש = to wag
• מכשכש = wagging / wags for a masculine singular subject

It also belongs to the present-participle style that Hebrew uses for present tense.

Because הכלב is a masculine singular noun, the verb has to match it.

So:

• הכלב מכשכש = the male dog / the dog (masc.) is wagging
• הכלבה מכשכשת = the female dog is wagging

Hebrew verbs in the present tense agree with the subject in gender and number.

Because the verb לכשכש is commonly used with the preposition ב־ when talking about the thing being wagged.

So Hebrew says, more literally:

• מכשכש בזנב = wags with the tail

rather than the English-style direct-object pattern wags the tail.

This is something English speakers often just have to learn as part of the verb’s natural Hebrew pattern. In other words, learn it as:

• לכשכש בזנב

not as a verb that normally takes את here.

This is a very common Hebrew spelling pattern.

The prepositions ב־ (in/at/with), ל־ (to/for), and כ־ (as/like) often merge with the definite article ה־.

So:

• ב + הזנב becomes בזנב

In unpointed Hebrew writing, the ה is not written separately here. The word is typically understood and pronounced as ba-zanav when it means with the tail / with the dog’s tail.

So even though you do not see ה, the definiteness is still there.

Hebrew often leaves possession unstated when it is obvious from context, especially with body parts.

So in this sentence, בזנב is naturally understood as with its tail because the subject is the dog.

If you want to make it more explicit, Hebrew can also say:

• הכלב מכשכש בזנבו = The dog is wagging its tail

Here ־ו means his/its.

So the original sentence is natural, and the possession is simply understood.

A good approximate pronunciation is:

• מכשכש = me-khash-KESH

The two כ letters here make the soft kh sound, like the ch in Scottish loch or German Bach.

So the whole sentence is approximately:

• ha-KE-lev me-khash-KESH ba-za-NAV

That is only an approximation for English speakers, but it is a useful starting point.

It can mean either one.

Hebrew present tense often covers both:

• The dog wags its tail
• The dog is wagging its tail

Context tells you which meaning is intended.

If you want to make right now clearer, you could add עכשיו:

• הכלב מכשכש בזנב עכשיו = The dog is wagging its tail now

That is because the verb comes from the root כ־ש־כ־ש, which has a repeated pattern. Hebrew has some verbs like this, and they often suggest repeated or back-and-forth movement or sound.

That repeated shape fits the meaning well here, because tail-wagging is a repeated motion.

So the form may look unusual if you are expecting only simple three-letter roots, but it is completely normal Hebrew.