The rugby player was exceptionally well-built, towering over most of his opponents.

well 是副词，表示"很好地、充分地"。 built 是动词 build 的过去分词，build 意思是"建造、构建"，这里指"体格构造"。 well-built 是复合形容词，字面意思是"建造得很好的"，用来形容人时表示"体格健壮的、身材匀称结实的"。