Denshi Jisho — Online Japanese dictionary

理由 りゆう reason; pretext; motive
Common word, Noun 
理由の原理 りゆうのげんり principle of reason (logic)
Noun 
理由をつける りゆうをつける to give a reason
Expression, Ichidan verb 
理由を付ける りゆうをつける to give a reason
Expression, Ichidan verb 

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