肥沃 (féi wò) is an adjective meaning 'fertile', used almost exclusively to describe soil that is rich in nutrients and highly suitable for growing crops or plants. The character 肥 (féi) literally means 'fat' or 'rich'—in this context, it conveys abundance of organic matter and nourishment. The character 沃 (wò) means 'irrigated', 'lush', or 'well-watered', emphasizing moisture retention and vitality. Together, they form a compound that evokes land teeming with life-supporting qualities: deep, dark, moist, and full of minerals.

This word is commonly found in agricultural, geographical, and environmental contexts—such as describing farmland, river deltas, or ecological reports. It’s rarely used metaphorically (unlike English 'fertile' which can describe ideas or minds), and never applied to people or animals. Native speakers typically pair it with nouns like 土壤 (soil), 土地 (land), or 农田 (farmland), and often modify it with degree adverbs like 非常 (very) or 十分 (extremely).