Architectus cum mensore fundamentum restituit.

Because architectus is in the nominative singular, the case normally used for the subject.

A learner will often recognize this from the -us ending, which is very common for a masculine second-declension nominative singular noun.

So here:

• architectus = the architect as the doer of the action

It is not the object, because Latin usually marks the direct object with the accusative, not the nominative.

Because the preposition cum meaning with takes the ablative case.

The noun mensor changes in the ablative singular to mensore. So:

• mensor = nominative singular, the surveyor as subject
• mensore = ablative singular, with the surveyor

That is why Latin says cum mensore.

Here it means with.

Latin cum can mean two different things:

• cum
  • ablative noun = with
• cum as a conjunction introducing a clause = when, since, or although

In this sentence, cum is followed by mensore, a noun in the ablative, so it is clearly the preposition meaning with.

If it meant when, you would expect a whole clause with a verb, for example something like cum mensor venit = when the surveyor comes/came.

Fundamentum is the accusative singular, and it is the direct object of the verb.

It is the thing being restored.

This can look slightly confusing at first because fundamentum is a neuter second-declension noun, and for neuter nouns the nominative and accusative singular are both -um. So the form fundamentum could be either nominative or accusative in isolation.

In this sentence, though, it must be accusative because:

• architectus is already the subject
• restituit needs something being restored
• so fundamentum is the object

Restituit is third person singular active indicative from restituo, restituere.

That means it goes with a singular subject such as architectus and means either:

• he/she/it restores — present
• he/she/it restored / has restored — perfect

This is an important point: restituit is one of those Latin forms that can be ambiguous by itself. Context tells you whether it is present or perfect.

So depending on the context, the sentence could mean:

• The architect restores the foundation with the surveyor
• or The architect restored the foundation with the surveyor

Because in Latin some verbs have a present third-person singular form and a perfect third-person singular form that happen to look identical.

For restituo:

• present: restituit = he restores
• perfect: restituit = he restored / has restored

Latin readers rely on context to tell which one is meant. For example:

• a narrative in past time may suggest restored
• a description of what someone usually does may suggest restores

This is very normal in Latin, even if it feels strange to an English speaker.

Because classical Latin has no articles.

So Latin does not normally have separate words for:

• the
• a / an

That means a noun like architectus can mean:

• the architect
• an architect
• sometimes just architect

The exact choice in English depends on context and on the most natural translation.

The same is true for:

• mensore = with the surveyor or with a surveyor
• fundamentum = the foundation or a foundation

Yes, it could be different. Latin word order is much freer than English word order because the endings show what each word is doing.

This sentence has a very normal Latin arrangement:

• Architectus first — the subject
• cum mensore together — the prepositional phrase
• fundamentum before the verb — the object
• restituit at the end — a very common place for the verb in Latin

Latin likes to keep cum close to its noun, so cum mensore naturally stays together.

Other word orders are possible, such as:

• Fundamentum architectus cum mensore restituit
• Architectus fundamentum cum mensore restituit

The meaning would stay basically the same, though the emphasis might shift.

A learner often wants to know how each form would appear in a dictionary. They are:

• architectus, architecti — architect
• mensor, mensoris — surveyor, measurer
• fundamentum, fundamenti — foundation
• restituo, restituere, restitui, restitutum — restore, rebuild, put back

These dictionary forms help you identify:

• the declension of a noun
• the conjugation of a verb
• the meanings of the basic form

Because mensore is not in the nominative case.

If Latin wanted to say the architect and the surveyor as two subjects, you would expect something like:

• architectus et mensor

But here we have:

• architectus — nominative singular subject
• cum mensore — ablative phrase meaning with the surveyor

So the surveyor is accompanying the architect, not acting as a second grammatical subject.