Aeger medicum adit.

It is an adjective by form, meaning sick or ill, but here it is being used substantively—that is, as if it were a noun. Latin often does this.

So aeger can mean:

• the sick man
• the sick person
• the patient (in context)

English usually has to add a noun, but Latin can leave it understood.

Because aeger is in the nominative case, which is the normal case for the subject of the sentence.

At the same time, medicum is in the accusative case, which is the normal case for a direct object.

So the sentence structure is:

• aeger = the one doing the action
• medicum = the one receiving the action

Because it is the direct object of the verb.

The dictionary form is medicus, meaning doctor. But when it is used as the direct object, it changes to the accusative singular: medicum.

So:

• medicus = doctor, as subject
• medicum = doctor, as object

Because the idea of to is already built into the verb adit.

This verb comes from adire, which means to go to, to approach, or to visit. Because of that, Latin does not need a separate preposition here.

So medicum adit is not word-for-word goes to doctor with a separate to; rather, adit already means something like goes to or approaches.

Adit is:

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

In simple English, it means he goes to, she goes to, or the sick person goes to.

The -t ending is the normal Latin ending for he/she/it in the present tense.

Because Latin words often cover a wider range of meaning than one single English word.

Adire can mean:

• to go to
• to approach
• to visit

In this sentence, English may choose different natural translations depending on context. All of them reflect the same basic Latin idea.

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

So Aeger medicum adit could be translated, depending on context, as:

• The sick man goes to the doctor
• A sick man goes to a doctor
• The patient visits the doctor

English has to choose an article, but Latin does not state one directly.

Word order matters less in Latin than in English, because the endings show the grammatical roles.

In this sentence:

• aeger is nominative, so it is the subject
• medicum is accusative, so it is the object

That means Latin could change the order without changing the basic meaning, for example:

• Aeger medicum adit
• Medicum aeger adit
• Adit aeger medicum

These all basically mean the same thing, though the emphasis may change.

Because aeger belongs to a group of adjectives whose masculine nominative singular ends in -er rather than -us.

Its forms are:

• aeger masculine
• aegra feminine
• aegrum neuter

This is just the normal dictionary pattern for that adjective. In other forms, the e often disappears, as in aegri.

So aeger is not irregular in the sense of being wrong; it is simply the correct nominative masculine singular form of that adjective.