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Definition of Shikoku
1. Noun. The smallest of the four main islands of Japan; to the south of Honshu and to the east of Kyushu; separated from Honshu by the Inland Sea; forested and mountainous. 
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1. Noun. The smallest of the four main islands of Japan; to the south of Honshu and to the east of Kyushu; separated from Honshu by the Inland Sea; forested and mountainous.