Learn Hardcore Italian: Sia la coinquilina sia il vicino sono occupati oggi. - Both the roommate and the neighbor are busy today.

No. In this sentence sia is a conjunction used in the pair sia … sia. You can tell because it’s followed by noun phrases (la coinquilina, il vicino) and the verb of the sentence is sono later on. As a verb, sia would appear in clauses like Spero che sia occupata.

Why is the verb plural (sono) and not singular (è)?

Because the subject is compound: la coinquilina + il vicino = they. Italian uses a plural verb for a coordinated (A + B) subject.

Why is it occupati and not occupata or occupate?

Adjectives agree in gender and number with the subject. With one female (coinquilina) and one male (vicino), the default plural is masculine: occupati.

Both female: Sia la coinquilina sia la vicina sono occupate oggi.
Both male: Sia il coinquilino sia il vicino sono occupati oggi.

Do I need the articles la and il before the nouns?

Yes. With specific singular nouns, Italian normally uses articles, and with sia … sia you typically repeat the article: sia la … sia il …. Omitting them here (sia coinquilina sia vicino) sounds wrong.

Can I use sia … che instead of sia … sia? What about just e?

Sia … che is fine and common: Sia la coinquilina che il vicino sono occupati oggi.
Plain e is also correct but less emphatic: La coinquilina e il vicino sono occupati oggi.
Avoid mixing patterns like sia … e.

How can I say “both of them are busy today” without naming them?

Entrambi sono occupati oggi. (mixed or all-male) / Entrambe sono occupate oggi. (all-female)
Tutti e due sono occupati oggi. (mixed or all-male) / Tutte e due sono occupate oggi. (all-female)

Where can oggi go in the sentence?

Common options:

End: … sono occupati oggi.
Beginning: Oggi sia la coinquilina sia il vicino sono occupati.
After the subject block: Sia la coinquilina sia il vicino oggi sono occupati.
All are acceptable; beginning or end is most natural.

Do I need commas with sia … sia?

No comma is needed: write Sia la coinquilina sia il vicino sono …. Commas may appear only if you insert extra parenthetical material.

What are the gender forms for “roommate” and “neighbor”?

Roommate: il coinquilino (m), la coinquilina (f)
Neighbor: il vicino (m), la vicina (f)

Does il vicino mean “the nearby one,” or specifically “the neighbor”?

With the article and used as a noun (il vicino / la vicina), it means “the neighbor.” Without an article, vicino is often an adverb/adjective meaning “near/nearby” (e.g., Il bar è vicino).

How do you pronounce the key words?

sia: SEE-ah
coinquilina: co-een-kwee-LEE-nah (stress on “li”)
vicino: vee-CHEE-no
occupati: ok-koo-PAH-tee (stress on “pa”)

Is sia … sia formal?

Neutral to slightly formal; common in writing and careful speech. In casual speech, many speakers use e, entrambi, or tutti e due.

Can I list more than two items with sia … sia?

Yes: you can extend it, repeating sia for each item: Sia la coinquilina, sia il vicino, sia l’amico di sopra sono occupati oggi.

Do I have to repeat sia before each item?

Yes, keep the structure balanced: sia A sia B (sia C …). Don’t drop the second sia.

Could I use impegnati instead of occupati?

Yes: impegnati often suggests having commitments/appointments, while occupati is broader (“busy,” “engaged,” even “line is busy”). Here both work, with a slight nuance difference.

Can I add loro as a subject pronoun?

It’s unnecessary here because the subjects are explicitly named. In Italian, subject pronouns are usually omitted unless needed for contrast: you would not say Loro la coinquilina e il vicino sono occupati. If the people were known from context, you could simply say Sono occupati oggi.