Denshi Jisho — Online Japanese dictionary

決心 けっしん determination; resolution
Common word, Noun, Suru verb 
決心が鈍る けっしんがにぶる to waver in one's resolution
Expression, Godan verb with ru ending 
決心が揺らぐ けっしんがゆらぐ to lose one's resolve; to have one's resolution waver
Expression, Godan verb with gu ending 
決心を固める けっしんをかためる to make a firm resolution
Expression, Ichidan verb 

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