болван

болван is a Russian noun meaning fool, idiot, or blockhead. It is insulting, though its strength ranges from mildly scolding to quite rude depending on tone and context.

It can also have older or specialized meanings, including a rough blank or dummy form used in manufacturing, and historically an idol or statue. The insulting sense likely developed from the idea of something inanimate or stupid.

Common related words include дурак (“fool”), идиот (“idiot”), тупица (“dimwit”), and кретин (“cretin”). A colloquial feminine form is болванка, though that word also commonly means a blank, dummy, or metal billet.

Examples:

1. Не будь болваном и проверь адрес перед отправкой письма.
   Don’t be a fool and check the address before sending the letter.
2. Я чувствовал себя болваном, когда понял, что забыл ключи дома.
   I felt like an idiot when I realized that I had left my keys at home.
3. Он назвал меня болваном из-за этой ошибки.
   He called me a blockhead because of that mistake.
4. Какой же я болван — весь день искал очки, а они были у меня на голове.
   What an idiot I am—I looked for my glasses all day, and they were on my head.
5. Не слушай его: он просто говорит, что все вокруг болваны.
   Don’t listen to him: he just says that everyone around him is an idiot.