Sospetto un errore.

Here it is a verb: sospetto = I suspect.

It is the first-person singular present tense of sospettare.

This word can also be:

• a noun: un sospetto = a suspicion
• an adjective: un tipo sospetto = a suspicious person / a suspect-looking guy

But in Sospetto un errore, the presence of un errore after it makes it clear that sospetto is being used as a verb.

Because Italian often drops subject pronouns when they are not needed.

The verb form sospetto already tells you the subject is I. So:

• Sospetto un errore = I suspect an error
• Io sospetto un errore = also correct, but io adds emphasis or contrast

For example:

• Io sospetto un errore, tu no.
  I suspect an error, you don’t.

So the version without io is the most neutral and natural one.

In Italian, you usually need an article with a singular countable noun.

So:

• un errore = an error / a mistake

Leaving out the article would sound incomplete in standard Italian:

• Sospetto errore ❌

Italian uses articles more often than English does, so this is a very common thing for English speakers to notice.

Because errore is a masculine singular noun beginning with a vowel, and the normal masculine indefinite article before a vowel is un.

So:

• un errore
• un amico
• un uomo

Uno is used before certain consonant sounds, such as:

• uno studente
• uno zaino
• uno psicologo

So uno errore is not correct.

Yes, errore is masculine singular.

You can tell from the article:

• un errore

Also, many Italian nouns ending in -ore are masculine:

• il colore
• il rumore
• l’amore
• l’errore

Its plural is:

• gli errori = the errors
• errori = errors

Yes, it is grammatical and understandable, but in everyday speech many Italians would more often say:

• Sospetto che ci sia un errore.
• Credo che ci sia un errore.
• Penso che ci sia un errore.

Why? Because in many contexts you are really saying I suspect that there is an error, not I suspect an error as a direct object.

So:

• Sospetto un errore = concise, correct, somewhat compact
• Sospetto che ci sia un errore = often more natural in conversation

No, not in this meaning.

With sospettare, when the thing suspected is the direct object, Italian normally uses no preposition:

• Sospetto un errore.
• Sospetto un problema.

Di appears in other structures, for example:

• Sospettare qualcuno di qualcosa = to suspect someone of something
• Lo sospettano di frode. = They suspect him of fraud.

So for this sentence, Sospetto di un errore is not the right pattern.

It is the present indicative.

From the infinitive sospettare:

• io sospetto = I suspect
• tu sospetti = you suspect
• lui/lei sospetta = he/she suspects
• noi sospettiamo = we suspect
• voi sospettate = you all suspect
• loro sospettano = they suspect

In this sentence, the present tense usually corresponds to English I suspect.

Usually, the best English equivalent is simply I suspect.

Italian present tense often covers both:

• a simple present idea
• something happening now

So sospetto can sometimes overlap with I’m suspecting, but in normal English I suspect is much more natural.

If Italian really wants to emphasize an ongoing action, it can use:

• Sto sospettando un errore

But that is less common here than plain Sospetto un errore.

Yes, but the difference is small.

• errore = error, often a bit more neutral or formal
• sbaglio = mistake, often a bit more everyday or conversational

So you could also say:

• Sospetto uno sbaglio.

That said, errore is very natural in contexts like writing, calculations, documents, grammar, and procedures.

A simple pronunciation guide is:

• sospetto ≈ so-SPET-to
• un ≈ oon (but very short)
• errore ≈ er-RO-re

A few useful points:

• sospetto has stress on -spet-
• errore has stress on -ro-
• the rr in errore is pronounced more strongly than a single English r

A rough full pronunciation is: so-SPET-to oon er-RO-re

You would use the direct object pronoun lo, because errore is masculine singular.

So:

• Sospetto un errore. becomes
• Lo sospetto.

That means I suspect it.

If the noun were feminine singular, you would use la instead.