Similarità vs. somiglianza vs. rassomiglianza

The Italian language offers three words to express the concept of similarity or resemblance: 'similarità', 'somiglianza', and 'rassomiglianza'. While they share a common theme, each word has subtle differences in usage and connotation.

Similarità

'Similarità' refers to a general similarity or likeness between things, often used in more formal or scientific contexts.
C'è una forte similarità tra le strutture molecolari di questi due composti.
(There is a strong similarity between the molecular structures of these two compounds.)
La similarità dei sintomi rende difficile la diagnosi.
(The similarity of symptoms makes diagnosis difficult.)

Somiglianza

'Somiglianza' is the most common and versatile term, used for physical resemblance as well as abstract similarities in everyday language.
La somiglianza tra padre e figlio è sorprendente.
(The resemblance between father and son is striking.)
C'è una certa somiglianza tra le due teorie.
(There is a certain similarity between the two theories.)

Rassomiglianza

'Rassomiglianza' emphasizes a strong or striking resemblance, often used for physical appearance or artistic representations.
Il ritratto mostra una perfetta rassomiglianza con il soggetto.
(The portrait shows a perfect likeness to the subject.)
La rassomiglianza tra i gemelli è quasi incredibile.
(The resemblance between the twins is almost unbelievable.)

Summary

While 'similarità' is often used in formal or scientific contexts to describe general likenesses, 'somiglianza' is the most versatile term for everyday use, covering both physical and abstract similarities. 'Rassomiglianza' tends to emphasize a strong or striking resemblance, particularly in physical appearance or artistic representation. The choice between these words depends on the context and the specific nuance the speaker wishes to convey.