Familinomo aperas sur la legitimilo.

In Esperanto, la is used when you mean a specific, identifiable thing. Here, familinomo is being used in a general or label-like way, almost like saying Family name appears on the ID card.

This style is common in forms, instructions, signs, and official language. It can sound a bit like a heading or category name.

If you said La familinomo aperas sur la legitimilo, that would mean the family name in a more ordinary sentence, referring to a specific family name already understood from context. Both are possible, but the version without la sounds more official or generic.

It is a compound word:

• famili- = family
• nomo = name

So familinomo literally means family name, that is, surname / last name.

Esperanto often builds words this way by combining meaningful parts.

Aperi means to appear or to show up / be shown.

The ending -as marks the present tense in Esperanto. So:

• aperi = to appear
• aperas = appears / is appearing

In this sentence, aperas is best understood as appears or is shown.

Sur means on, while en means in.

Since writing or printed information is usually said to be on a document, card, page, label, or screen, Esperanto commonly uses sur:

• sur la paĝo = on the page
• sur la karto = on the card
• sur la legitimilo = on the ID card

Using en would suggest something more like inside the document, which is not the usual idea here.

Legitimilo is a noun meaning something like ID card, identity document, or credential.

It comes from:

• legitimi = to authenticate / to make legitimate
• -ilo = tool or instrument

So legitimilo literally means a thing used for identification or authentication.

Depending on context, it could refer to an ID card, pass, badge, or similar official document.

Because it is not the direct object of the verb.

In the sentence:

• Familinomo = subject
• aperas = verb
• sur la legitimilo = prepositional phrase

The preposition sur already shows the role of la legitimilo, so you do not add -n there.

The accusative -n is mainly used for direct objects and for motion toward something in certain cases. Here, there is no direct object.

Yes. Familinomo is the subject, because it is the thing that appears.

So the structure is:

• Familinomo = the family name
• aperas = appears
• sur la legitimilo = on the ID card

A good literal breakdown is:

Family name appears on the ID card.

Yes. Esperanto word order is fairly flexible, because endings and prepositions help show the grammatical roles.

You could also say:

• Sur la legitimilo aperas familinomo.

This changes the emphasis a bit, but the basic meaning stays the same.

Still, Familinomo aperas sur la legitimilo is a very natural order, especially in neutral or official-style language.

You might be understood, but familinomo is the standard, established word for surname / family name.

• familinomo = family name, surname
• familia nomo would more literally suggest a family-related name, which is less precise

So for normal usage, especially in official contexts, familinomo is the better choice.

It is natural, but it has a somewhat official, administrative, or form-like feel.

That comes mainly from:

• the bare noun familinomo without la
• the formal word legitimilo

In everyday speech, someone might say something a little more conversational, but this sentence is perfectly normal in contexts like documents, instructions, forms, or official descriptions.