For a written letter:
* Lettre is the most common and general translation.
For a letter of the alphabet:
* Lettre is also used for a single letter of the alphabet.
For a letter as a symbol or sign:
* Lettre can still be used, but other options like signe or symbole might be more appropriate depending on the specific context.
Example:
* "I received a letter from my friend." - J'ai reçu une lettre de mon ami.
* "The letter 'A' is the first letter of the alphabet." - La lettre 'A' est la première lettre de l'alphabet.
It's important to consider the context to choose the most accurate translation.