Diary
Journal
noun
When you write down your day (and do it every day) that's your diary.
This is a jukugo word, which usually means on'yomi readings from the kanji. Since 日 has two on'yomi readings, here's a mnemonic to help you remember which one to use:
When you write down your day in your diary, in fact you write only about Nicky (にっき). You love Nicky so much, your diary is full of Nicky this, Nicky that. Ah, Nicky is just the best.
テーブルの上の日記は見ないで下さい。
Please do not look at the diary on the table.
毎日、日記をかくのに三十分くらいかかります。
It takes about 30 minutes to write a journal every day.
この日記のカバーは一万円でした。
The cover of this diary was 10,000 yen.