What does diary mean?
A diary is a book in which a person records events, experiences, and thoughts day by day. It can also mean a dated planner used to schedule appointments, a sense especially common in British English. Diaries occupy a unique position between the private and the public: most are intensely personal documents never meant for other eyes, yet published diaries — from Samuel Pepys's account of Restoration London to Anne Frank's writings in hiding — have become some of history's most valued records, offering intimate firsthand views of their times. The word derives from Latin 'dies', meaning 'day', reflecting its core idea of a daily account. To 'keep a diary' is a long-standing habit associated with reflection, self-discipline, and memory-keeping. A writer of diaries is known as a diarist. Whether used for private confession, creative practice, or simple organization, the diary remains a widely understood symbol of personal record-keeping across English-speaking cultures.
nounA book in which one keeps a daily record of events, experiences, and personal thoughts; also, a planner or datebook used to note appointments and engagements.
- A book in which a person records daily events, experiences, and reflections.
- A dated planner or appointment book in which one schedules engagements.
"She has kept a diary since she was twelve, filling notebook after notebook with her private thoughts."
"He wrote an entry in his diary every night before going to bed."
"Let me check my diary to see if I'm free on Thursday afternoon."
Standard plural, following the regular -y → -ies pattern for nouns ending in a consonant + y.
"The archive contains dozens of diaries kept by soldiers during the war."
Samuel Pepys's diary, written in shorthand code, wasn't deciphered for over a century — and it remains our most vivid eyewitness account of 17th-century London, including the Great Fire of 1666.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of diary
The word 'diary' comes from the Latin 'dies', meaning 'day', via the medieval Latin 'diarium', a daily allowance or journal of daily happenings. It entered English in the late sixteenth century, when the practice of keeping regular written records of one's days was spreading among educated readers. The same Latin root gives us related words such as 'diurnal' and 'meridian', all built on the idea of a day.
Related word forms
How diary is actually used
In British English, 'diary' commonly refers to a personal organizer or appointment book as well as a record of daily life; American English more often uses 'planner' or 'datebook' for the scheduling sense. The word carries connotations of privacy and introspection — a diary is typically assumed to be personal and not intended for public reading, which makes 'published diaries' notable by contrast. A person who keeps a diary is called a 'diarist'.
Easily confused with diary
A 'dairy' is a place where milk is produced or milk products are made and sold, while a 'diary' is a book for recording daily events — they differ only in the order of two vowels.