Supercilium supra oculum est.

Because supercilium is the subject of the sentence: it is the thing being described.

In Supercilium supra oculum est, the basic structure is:

• supercilium = the eyebrow
• est = is

So supercilium is the thing that is somewhere, and subjects are normally put in the nominative case.

Also, supercilium is a neuter second-declension noun, and here it is nominative singular.

Because supra takes the accusative.

So in this sentence:

• supra = above
• oculum = eye, in the accusative singular

Even though English uses above the eye without showing any case ending, Latin marks the noun after supra with the accusative.

A learner might expect some kind of locative idea to use the ablative, but with supra, standard Latin uses the accusative.

No. Even though oculum is accusative, it is not the direct object.

It is the object of the preposition supra.

So the sentence is not saying that the eyebrow is doing something to the eye. It is simply giving the eyebrow’s position relative to the eye.

Latin word order is much more flexible than English word order because Latin shows grammatical relationships through endings, not mainly through position.

This sentence could also appear as:

• Supercilium est supra oculum
• Supra oculum supercilium est

All of these can mean the same thing.

That said, putting est at the end is very common in simple Latin sentences, so Supercilium supra oculum est feels perfectly normal.

Because Latin has no definite article and no indefinite article.

So Latin does not have separate words for:

• the eyebrow
• an eyebrow

Both ideas can be expressed simply by supercilium, and the exact sense depends on context.

Likewise, oculum can mean:

• the eye
• an eye

English requires an article, but Latin does not.

Yes, but Latin often uses the singular when talking about something in a simple, general, or illustrative way.

So this sentence is just giving a basic fact about position:

• the eyebrow is above the eye

If you wanted the plural, you could say:

• Supercilia supra oculos sunt = The eyebrows are above the eyes

Using the singular here is completely normal, especially in beginner sentences.

Est is the third-person singular present tense of the verb sum, which means to be.

So:

• sum = I am
• es = you are
• est = he/she/it is

Here it matches the singular subject supercilium, so est means is.

Sometimes, yes, especially in certain styles such as poetry, inscriptions, or very compressed expressions. But in ordinary beginner prose, it is usually included.

So for a clear basic sentence, Supercilium supra oculum est is the normal full form.

Yes, they are related in the sense that both involve the idea of being above.

• supra is a preposition meaning above
• supercilium is a noun meaning eyebrow

A learner may notice the similar beginning super-/supra-, and that is not an accident: both are connected with the idea of something being over or above.

But grammatically they are completely different kinds of words:

• supercilium = noun
• supra = preposition

A common Classical Latin pronunciation would be approximately:

• supercilium = soo-per-KIL-ee-um
• supra = SOO-pra
• oculum = OK-oo-lum
• est = est

So the whole sentence is roughly:

soo-per-KIL-ee-um SOO-pra OK-oo-lum est

If you are learning Ecclesiastical Latin, the pronunciation may differ somewhat, especially in how c is pronounced before certain vowels. But in this sentence, a hard k sound for c is standard in Classical pronunciation.

A good way to group it is:

• Supercilium = subject
• supra oculum = prepositional phrase
• est = verb

So the sentence breaks down as:

[The eyebrow] [is above the eye].

In Latin, recognizing case endings and prepositions helps much more than relying only on word order. Here, supra tells you that oculum goes with it, forming one unit: above the eye.