Inadatto vs. inappropriato vs. inopportuno
While the Italian words inadatto, inappropriato, and inopportuno all generally mean unsuitable, they address different aspects of why something does not fit: functional incapacity, violation of social norms, or bad timing.
Inadatto
B2Inadatto refers to a lack of capability, suitability, or fitness for a specific purpose. It implies that the subject does not have the right skills, dimensions, or characteristics to perform a task.
Il candidato si è rivelato inadatto per il ruolo di manager.
(The candidate turned out to be unsuitable for the manager role.)
Queste scarpe sono inadatte per camminare sulla neve.
(These shoes are unsuitable for walking on snow.)
Quel film violento è inadatto ai bambini piccoli.
(That violent movie is unsuitable for small children.)
Questo strumento è inadatto per aggiustare un orologio.
(This tool is unsuitable for fixing a watch.)
Inappropriato
B2Inappropriato deals with etiquette and social context. It describes behavior, language, or appearance that is out of place, slightly offensive, or disrespectful given the specific social situation.
Il suo commento sarcastico è stato inappropriato durante il funerale.
(His sarcastic comment was inappropriate during the funeral.)
È inappropriato indossare un costume da bagno in un ristorante elegante.
(It is inappropriate to wear a swimsuit in a fine dining restaurant.)
Il professore ha usato un linguaggio inappropriato in classe.
(The professor used inappropriate language in class.)
Ridere dei problemi altrui è un comportamento inappropriato.
(Laughing at others' problems is inappropriate behavior.)
Inopportuno
B2Inopportuno focuses almost exclusively on timing. It describes an action that occurs at the wrong moment, causing inconvenience, awkwardness, or annoyance, even if the action itself is not inherently bad.
La tua chiamata è arrivata in un momento inopportuno.
(Your call came at an inopportune moment.)
Fare quella domanda mentre era arrabbiato è stato inopportuno.
(Asking that question while he was angry was ill-timed.)
Una visita inopportuna ci ha costretti a cambiare i nostri piani.
(An untimely visit forced us to change our plans.)
È inopportuno discutere di soldi durante la cena di Natale.
(It is unsuitable to discuss money during Christmas dinner.)
Summary
To choose the right word, identify the flaw: use inadatto if it doesn't work or fit the specific function; use inappropriato if it is rude or socially unacceptable; and use inopportuno if it is simply happening at the wrong time.