You encounter the compound words, the jukugo . These are the heavy lifters of the N4 level. They are built of kanji that stand like pillars. Taikutsu (boredom)—written with the characters for "exhaustion" and "moment." It suggests that boredom is not a lack of activity, but an exhaustion of the moment.
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Vocabulary is studied based on its grammatical role and how it functions in sentences.