洋芋 (yángyù): potato (dialect)

洋芋 is the dialect word for potato common in southwestern China (Yunnan, Guizhou, Sichuan, Shaanxi). Standard Mandarin uses 土豆 (tǔdòu) in the north and 马铃薯 (mǎlíngshǔ) in formal/scientific writing. The 洋 ('foreign') reflects that potatoes were imported from the Americas.

memory

洋 = 'foreign/Western', 芋 = 'taro'. So 洋芋 literally means 'foreign taro' — what Chinese farmers called this strange new tuber when it arrived from the New World.