diary

noun

di·​a·​ry ˈdī-(ə-)rē 

plural diaries

1

: a record of events, transactions, or observations kept daily or at frequent intervals : journal

especially : a daily record of personal activities, reflections, or feelings

2

: a book intended or used for a diary

Synonyms of diary

• journal

Examples of diary in a Sentence

has diligently kept a diary since she was 15

Recent Examples on the Web

These intimate reflections read like pages taken from private diaries, with all the informality and vulnerability of that genre, including misspellings and stray thoughts. —Casey Cep, New Yorker, 9 May 2026

The studies cited used set caffeine doses or placebos and tracked participants with brain-wave monitoring, sleep diaries and questionnaires across hundreds to thousands of people. —Samantha Agate, Sacbee.com, 5 May 2026

Kang amasses writings from over the course of her career, beginning with her Nobel lecture and reaching deep into her life’s documents, with diaries, poems, and photographs. —Literary Hub, 4 May 2026

Kummer was dressed on this day as Jacob Hiltzheimer, a German immigrant and silversmith who kept detailed diaries of life in the Revolutionary period. —Phaedra Trethan, USA Today, 4 May 2026

Word History

Etymology

Latin diarium, from dies day — more at deity

First Known Use

1581, in the meaning defined at sense 1

Phrases Containing diary

• keep a diary

Rhymes for diary

• fiery
• friary
• priory

Kids Definition

diary

noun

di·​a·​ry ˈdī-(ə-)rē 

plural diaries

: a daily record especially of personal experiences and thoughts

also : a book for keeping such a record

Etymology

from Latin diarium "a record of business dealings or activities during the day," from dies "day" — related to meridian, sunday see Word History at sunday