Cubby : A small room; a cubbyhole; a small secluded room; a small compartment.
有小房间, 小隔间(橱),隐蔽的小房间, 等等意思. 具体翻译要看上下文而定.
It's in the cubby-hole under the stairs.
它在楼下的小储藏间里。
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