To write in or maintain a diary; to record events and thoughts in a daily written record.
From 'diary' + English verb suffix '-ize' (to make or practice), creating a back-formation from the noun 'diarist'.
The verb 'diarize' is relatively new in English—it emerged as people started using diaries more casually, and apps like digital calendars now let you 'diarize' your schedule.
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