Silenzioso vs. tranquillo vs. zitto

The Italian words 'silenzioso', 'tranquillo', and 'zitto' all relate to silence or quietness, but they have distinct uses and connotations.

Silenzioso

'Silenzioso' means silent or quiet, typically referring to a lack of noise or sound in an environment or from an object.
La biblioteca è un luogo silenzioso.
(The library is a quiet place.)
Ho comprato un aspirapolvere silenzioso.
(I bought a quiet vacuum cleaner.)

Tranquillo

'Tranquillo' means calm, peaceful, or undisturbed. It can refer to both environments and people's states of mind.
Il lago era tranquillo questa mattina.
(The lake was calm this morning.)
Rimani tranquillo, andrà tutto bene.
(Stay calm, everything will be fine.)

Zitto

'Zitto' means quiet in the sense of not speaking or making noise, often used as a command or to describe someone who is not talking.
Stai zitto, per favore!
(Be quiet, please!)
Durante il film, tutti sono rimasti zitti.
(During the movie, everyone remained quiet.)

Summary

While 'silenzioso' describes a general absence of noise, 'tranquillo' implies a peaceful state beyond just quietness, and 'zitto' specifically refers to the act of not speaking or making noise, often used as a command.