Cardo decumanum secat.

Because Latin usually shows a word’s role by its case, not mainly by word order.

• cardo is nominative singular, which is the case normally used for the subject
• decumanum is accusative singular, which is the case normally used for the direct object

So cardo is the thing doing the action, and decumanum is the thing the action is done to.

That -um ending marks it as accusative singular here.

The basic form is decumanus. In this sentence, it is the direct object of secat, so it changes form:

• nominative singular: decumanus
• accusative singular: decumanum

English usually does not change nouns this way, so this is a very common thing for learners to notice in Latin.

Because cardo is a third-declension noun, not a second-declension noun.

A native English speaker often expects masculine Latin nouns to look like -us words, but many do not. The dictionary form is:

• cardo, cardinis

That means its nominative singular is simply cardo. So cardo is already the correct subject form.

Secat is:

• third person singular
• present tense
• active voice
• indicative mood

It comes from seco, secare, meaning to cut.

So secat means he/she/it cuts, or in smoother English sometimes is cutting, depending on context.

It can mean either in the right context.

Latin’s present tense often covers both:

• simple present: cuts
• progressive present: is cutting

In a short sentence like this, English usually chooses whichever sounds more natural from the context.

Classical Latin does not have articles like English the or a/an.

So a noun like cardo can mean:

• the cardo
• a cardo

and decumanum can mean:

• the decumanus
• a decumanus

Context tells you which English article makes the most sense.

It matters less in Latin than in English, because the endings already show the grammar.

So these can all express the same basic idea:

• Cardo decumanum secat
• Cardo secat decumanum
• Decumanum cardo secat

The difference is usually one of emphasis or style, not basic meaning.

In this sentence, Cardo decumanum secat is a straightforward, natural order: subject, object, verb.

Because the ending of the verb already tells you the subject is third person singular.

The -t in secat means he/she/it. Latin often leaves subject pronouns unstated unless they are needed for emphasis or clarity.

So Latin does not need to say a separate it cuts unless there is some special reason to do so.

They are:

• cardo, cardinis = cardo
• decumanus, -i = decumanus
• seco, secare = cut

This is useful because Latin sentences often contain changed forms, and the dictionary usually lists the base form, not the exact form you see in the sentence.

• cardo is a third-declension noun
• decumanus is a second-declension noun
• seco, secare is a first-conjugation verb

A learner often asks this because it helps explain why the words change in different ways:

• cardo does not behave like an -us noun
• decumanus does behave like an -us noun
• secat follows the present-tense pattern of a first-conjugation verb

In a common reconstructed Classical pronunciation, it would be approximately:

• CAR-do deh-koo-MAH-noom SEH-kat

A few helpful points:

• c is always hard, like k
• v is not present here, but in Classical Latin it is usually pronounced like w
• the stress falls on -ma- in decumanum

If macrons are shown, you may see something like Cardō decumānum secat, which marks vowel length.