This is the 8403rd most frequent Chinese word.
nikki
The word "nikki" is not Chinese; it is Japanese and means "diary" or "journal."
Here, 'Nikki' is used as a proper noun, referring to someone's name, who is the author of the diary.
昨天我看了Nikki写的日记，里面充满了她对生活的思考。
Yesterday, I read Nikki's diary, which was filled with her reflections on life.
In this sentence, 'Nikki' continues to act as a proper noun, referring to the same person who is regular in maintaining a diary.
Nikki总是把她的日记记得很详细，清晰地表达她的感受。
Nikki always writes her diary in great detail, clearly expressing her feelings.
Again, 'Nikki' is a proper noun indicating a character in a story, emphasizing her habit of writing diaries.