This row appears to be a data error: the pinyin 'de' does not match any standard reading of 底谷 (expected dǐ gǔ). Most likely it is a typo for 低谷 (dīgǔ), meaning 'low point' or 'trough' (in business, emotions, etc.). Use with caution; the headword 底谷 is not a common Chinese word.