日記
にっき · nikki · JLPT N4 · noun
diary
📔 日記 = day + record: a record kept day by day
日 means day (as in 日本, 日曜日) and 記 means to write down or record (as in 記事 article, 記者 reporter). The small っ doubles the k: nichi + ki contracts to nikki. A daily record is a diary.
日 — pictograph of the sun
日 is a pictograph of the sun, originally drawn as a circle with a dot or stroke inside representing the sun's substance. Over time the round shape was squared off into the modern rectangular form. It means 'sun' and by extension 'day'.