General "silly":
* глупый (gloo-py) - This is the most common and direct translation of "silly". It implies a lack of intelligence or common sense.
* нелепый (ne-le-py) - This word suggests something absurd or illogical, often in a humorous way.
More playful or affectionate "silly":
* дурачок (doo-ra-chok) - This word is a playful way to call someone silly, often used with friends or children. It can be considered slightly endearing.
* глупенький (gloo-pen-kee) - This is a softer version of "глупый" and can be used to express amusement or affection.
Other options:
* смешной (sme-sh-noy) - This word means "funny" but can also be used to describe something silly or ridiculous.
* несерьезный (ne-se-ryoz-ny) - This literally means "not serious", and can be used to describe someone who is silly or frivolous.
The best choice will depend on the specific situation and your intended meaning.