「つまらない」 (Tsumaranai) is an i-adjective meaning 'boring' or 'dull'. It describes something that is not interesting, lacks excitement, or fails to engage. It can refer to a book, movie, conversation, or situation that you find unstimulating.

「つまらない」は「boring, dull」という意味のい形容詞です。興味がなく、面白くないことを表します。