ETYM Latin diarium, from dies day. Related to Deity.
1. A daily written record of (usually personal) experiences and observations; SYN. journal.
2. A personal record book (as a physical object).
Informal record of day-to-day events, observations, or reflections, usually not intended for a general readership. One of the earliest diaries extant is that of a Japanese noblewoman, the Kagero Nikki 954–974, and the earliest known diary in English is that of Edward VI (ruled 1547–53). Notable diaries include those of Samuel Pepys and Anne Frank.
The writer John Evelyn, the Quaker George Fox, and in the 20th century the writers André Gide and Katherine Mansfield were also diarists.