1. written account of daily occurrences, journal; daily calendar. diarydia*ry , n.; pl. diaries (#). [l. diarium, fr. dies day. see: deity.] a register of daily events or transactions; a daily record; a journal; a blank book dated for the record of daily memoranda; as, a diary of the weather; a physician's diary.diary dia*ry, a. lasting for one day; as, a diary fever. [obs.] diary ague