Italian Phrase
Cos'è un rilevatore di fumo?
Meaning
The sentence asks for a definition: ‘What is a smoke detector?’ It is used when you want to know the function, purpose, or legal requirements of a device that senses smoke and triggers an alarm.
When to use
Use this question in safety‑related conversations, during a home‑inspection, in a classroom discussion about fire prevention, or when you’re reading a manual and encounter the term ‘rilevatore di fumo’. It’s a polite, neutral way to request clarification.
✦Grammar Breakdown
Cos'èunrilevatoredifumo?
Cos' (cosa + apostrophe)
‘Cos’’ is the contraction of ‘cosa’ before a vowel; it means ‘what’.
è (essere)
Third‑person singular present of ‘essere’, used here to ask for a definition.
un (indefinite article)
The masculine singular indefinite article used before a consonant‑starting noun.
rilevatore (noun)
Means ‘detector’; it follows the article ‘un’ and can be qualified by a prepositional phrase.
di (preposition)
Links the detector to what it detects – in this case ‘fumo’ (smoke).
fumo (noun)
Means ‘smoke’; together with ‘di’ it forms the complement ‘di fumo’ (of smoke).
🗨In Conversation
Cos'è un rilevatore di fumo?
What is a smoke detector?
È un dispositivo che avverte la presenza di fumo, attivando un allarme per avvisare le persone di un possibile incendio.
It’s a device that warns of the presence of smoke by sounding an alarm to alert people of a possible fire.
✕Common Mistakes
Cosa è un rilevatore di fumo?
‘Cosa è’ is not idiomatic; the correct form is the contraction ‘Cos’è’ or ‘Che cos’è’.
Un' rilevatore di fumo?
The article ‘un’ is masculine; do not use the apostrophe. ‘Un’ + consonant, not ‘un’ + vowel.
Cos'è un rilevatore di fumi?
‘Fumo’ is singular; the device detects smoke in general, not plural ‘fumi’.
↔Alternatives
Che cos'è un rilevatore di fumo?
What is a smoke detector?
Che cosa è un rilevatore di fumo?
What is a smoke detector?
Che tipo di dispositivo è un rilevatore di fumo?
What kind of device is a smoke detector?
Cultural Tip
In Italy, the installation of smoke detectors (rilevatori di fumo) is mandatory in new residential buildings and in many public spaces since the 2015 fire‑safety law. The devices must be certified (CE mark) and are often connected to a central alarm system in apartment blocks. When discussing safety in Italy, it’s common to mention the legal requirement, not just the technical function.