How do you say Ils sont fidèles in feminine?

The feminine plural form of "Ils sont fidèles" (They are faithful) is Elles sont fidèles.

Here's why:

* Ils is the masculine plural pronoun for "they".

* Elles is the feminine plural pronoun for "they".

* sont is the third-person plural form of the verb "être" (to be) and doesn't change based on gender.

* fidèles is an adjective that agrees in gender and number with the subject.

Therefore, to make the phrase feminine, we simply replace "ils" with "elles".