noun
small isolated island
Refers to a tiny island that is separated from the mainland or a larger island, often with a sense of remoteness.
沖合に離れ小島が見える。
A small isolated island is visible offshore.
孤島 is a more formal or literary term for a solitary island, while 離れ小島 emphasizes smallness and separation in a more descriptive, everyday way.
Compound of 離れ (はなれ, 'separated') + 小島 (こじま, 'small island'). The exact historical derivation is uncertain, but the word transparently describes a small island that is set apart from others.