Diary (noun)

1. A book in which one keeps a daily record of events, experiences, and observations.
2. A personal record of events and experiences written in a book on a daily basis.
3. A book in which one records one's private thoughts and feelings.
4. A record of events, observations, or experiences written down on a regular basis.
5. A daily journal in which one records one's thoughts, feelings, and observations.

Origin:

Early 17th century: from french diarie, from latin diarium "daily allowance", from dies "day".

Examples:

1. She kept a diary of her trip to Europe.
2. The diary was a personal record of his thoughts and feelings.
3. The diary was filled with daily entries.
4. He wrote in his diary every night before bed.
5. The diary was a valuable historical document.