沃 most commonly appears in 肥沃 (féiwò, fertile). It is also used as a phonetic transliteration character in brand names like 沃尔玛 (Walmart) and 沃尔沃 (Volvo).
Left water radical, the side-form of 水, three abbreviated waves. Marks 沃 as a water-action: to irrigate, to water richly. From 'well-watered land' came the metaphorical sense of 'fertile, rich (soil).' Same radical in 河, 海, 湖, 流, 浇.
Right 夭 supplies the sound, yāo drifted to wò through Old Chinese palatal and rounding shifts. 夭 itself depicts a young person with head tilted, hence 'young' or 'die young.' The faint semantic echo of 'young, lively' matches the lush vegetation of fertile land.
