...they defined "the best" as staying home to help support the family. (Para. 4)
define as: state the meaning of (something such as a word) as being (something)
It's wrong to define "happiness" as "owing lots of money". 把 "幸福"界定为 "拥有很多钱"是错误的。
adj. 有定义的,确定的;清晰的,轮廓分明的 v. 使