fundament
noun [ C ] formal uk/ˈfʌn.də.mənt/ us/ˈfʌn.də.mənt/
(BASIS)
基础，根本
the most important facts, ideas, etc. from which something is developed
Loss is the underlying fundament of romantic music. 怅然若失的感觉是浪漫主义音乐的基础。
Synonym: basis (IMPORTANT FACTS)
(PART OF BODY)
（人的）臀部
a person's bottom