Canis vagus per vias ambulat.

Canis is nominative singular. In Latin, the subject of a finite verb is usually in the nominative case, and here the verb is ambulat, which is he/she/it walks. So canis is the thing doing the walking.

A learner can also recognize canis as the dictionary form of the noun canis, canis.

Vagus is an adjective describing canis, so it must agree with the noun in case, number, and gender.

Here it is:

• nominative
• singular
• masculine

That matches the way canis is being treated in this sentence. So vagus means the adjective is agreeing correctly with the subject noun.

Because the adjective is being used in the masculine singular nominative form.

The noun canis can refer to a male or female dog, but in this sentence the adjective shows that the dog is being treated as masculine:

• masculine: vagus
• feminine: vaga

So if the sentence were describing a female dog, you would expect canis vaga.

Because the preposition per takes the accusative case.

So:

• per viam = through the road / along the road
• per vias = through the roads / along the streets

This is something Latin learners have to memorize: many prepositions regularly govern a specific case, and per governs the accusative.

Here per means something like:

• through
• along
• by way of

With a word like vias, English often translates it naturally as through the streets or along the roads, depending on context.

So the basic idea is movement through or along an area or route.

Because the sentence is talking about movement through streets/roads in the plural.

• via = road, street, way
• vias = roads, streets, ways

Latin is being more specific here: not just along one road, but through multiple streets or roads. If it were singular, it would be per viam.

Ambulat is:

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

It comes from ambulare, meaning to walk.

So ambulat means he walks, she walks, or it walks, depending on the subject.

Because the subject, canis, is singular.

Latin verbs agree with their subject in number:

• singular subject → singular verb
• plural subject → plural verb

So:

• canis ambulat = the dog walks
• canes ambulant = the dogs walk

Because Latin adjectives can appear before or after the noun they modify.

So both noun-adjective and adjective-noun orders are possible in Latin. Putting the adjective after the noun is very normal:

• canis vagus
• vagus canis

Both are possible, though word order can sometimes slightly affect emphasis or style.

Latin often places the verb toward the end, especially in straightforward prose and textbook examples. That does not mean it has to be there, but it is a very common pattern.

So this sentence follows a familiar Latin structure:

• subject: canis
• description: vagus
• prepositional phrase: per vias
• verb: ambulat

A learner should get used to seeing verbs at the end, even though Latin word order is more flexible than English word order.

Yes, often they could.

For example, these would still be understandable Latin:

• Per vias canis vagus ambulat
• Canis per vias vagus ambulat
• Ambulat canis vagus per vias

The endings show the grammatical roles, so Latin does not rely on word order as heavily as English does. However, different orders can create different emphasis or sound more or less natural in a given context.

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

So canis can mean:

• a dog
• the dog

Which one is best depends on the context. English must choose an article, but Latin usually leaves that information unstated unless the context makes it clear.

Yes. Canis belongs to the third declension.

Its basic forms are often given as:

• canis = nominative singular
• canis = genitive singular

That is why its nominative singular does not look like a first- or second-declension noun such as puella or servus.

In a Classical Latin pronunciation, an approximate English guide would be:

KAH-nees WAH-goos pehr WEE-ahs ahm-BUH-laht

A few useful points:

• c is always hard, as in cat
• v is pronounced like w in Classical Latin
• g is always hard, as in go
• a is always pronounced clearly, never like the weak vowel in English about

If you are learning Ecclesiastical Latin, the pronunciation of v would sound more like English v instead.