chief 拽人时，表同类中职位最高，权力最大；指物时，表同类中最重要，价值最高。
principal 用于人时，指地位优于其他人；用于物时，指该物在大小、重要性等方面优于他物。
main 通常只用于物。指在一定范围内，某物的重要性、体积或力量等超过其它物。
major 指同其他人或其它物、问题等相比较，显得更加重要和突出。
leading 侧重指具有影响力或凝聚力。从而有主导和引导的作用。
capital 着重指因重要性、意义、优越或重大而名列同类之首。
foremost 侧重指在行进或发展过程中居首位。
primary 通常不用于人。用于物时，指在重要性方面占第一位。
参考例句
1. Every axis has a principal node type . 每个轴具有一个主节点类型。
2. As the Principal of the school I work closely with each grade 12 student. 作为学校的校长，我和12年级学生保持紧密工作和联系。
3. All of the animals excepting man know that the principal business of life is to enjoy it. 除了人类之外，所有的动物都懂得，生活首要的事情是享受生活。——巴特勒。
英英解释
n.
1. the original amount of a debt on which interest is calculated
2. the educator who has executive authority for a school
3. an actor who plays a principal role
4. capital as contrasted with the income derived from it
5. the major party to a financial transaction at a stock exchange; buys and sells for his own account adj.
1. most important element
