principal

chief, principal, main, major, leading, capital, foremost, primary

名词 principal:

1. the original amount of a debt on which interest is calculated
2. the educator who has executive authority for a school
   同义词：school principal, head teacher, head
3. an actor who plays a principal role
   同义词：star, lead
4. capital as contrasted with the income derived from it
   同义词：corpus, principal sum
5. the major party to a financial transaction at a stock exchange; buys and sells for his own account
   同义词：dealer

形容词 principal:

1. most important element
   同义词：chief, main, primary

1. My principal concern is my family's welfare.
   我至为关心的是我一家的幸福。
2. The agent spoke on behalf of his principal.
   代理人代表他的委托人说话。
3. How much interest will there be on a principal of $5000?
   5000美元本金的利息是多少？
4. Keys are available on application to the principal.
   向校长申请就可得到钥匙。
5. I will have to consult my principals before I can give you an answer on that.
   我必须同我的委托人磋商后才能就这个问题给你答复。
6. My wages are the principal source of my income.
   薪金是我收入的主要来源。
7. Our principal problem is lack of time.
   我们的主要问题就是缺少时间。

prin.ci.pal

adj.Abbr. prin.（形容词）缩写 prin.
First, highest, or foremost in importance, rank, worth, or degree; chief.See Synonyms at chief
重要的，首要的：重要性，地位，价值或程度上处于首要的，最高的或最重要的参见 chief
Of, relating to, or being financial principal, or a principal in a financial transaction.
本金的，资本的：属于或关于本金的或财政周转中的资金的
n.Abbr. prin.（名词）缩写 prin.
One who holds a position of presiding rank, especially the head of an elementary school or high school.
首长，负责人：处于最高地位的人，尤指小学或高中校长
A main participant in a situation.
首要参与者：某一形势中的主要参加者
A person having a leading or starring role.
主要演员，主角：担任领导或主要角色的人

The capital or main body of an estate or a financial holding as distinguished from the interest or revenue from it.
本金，资本：财产或金融资产的资本或主体，区别于由它得来的利息或收益
A sum of money owed as a debt, upon which interest is calculated.
本金：作为债务的一笔钱，以此为基础来计算利息
Law
【法律】
A person who empowers another to act as his or her representative.
委托人：授权另一人代表他或她行事的人
The person having prime responsibility for an obligation as distinguished from one who acts as surety or as an endorser.
当事人：对某一义务负首要责任的人，区别于担保人或背书转让人
One who commits or is an accomplice to a crime.
主犯：进行犯罪活动或协助犯罪活动的人
The main truss or rafter that supports and gives form to a roof.
橼木：构成或加固屋顶用的桁架或橼木

来源：
Middle English
中古英语
from Old French
源自 古法语
from Latin proncip3lis
源自 拉丁语 proncip3lis
from pronceps proncip- [leader, emperor] * see per
源自 pronceps proncip- [领导，国王] *参见 per

【引伸】
prin.cipally
adv.（副词）
prin.cipalship.
n.（名词）
Principal and principle are often confused but have no meanings in common. Principle is only a noun, and most of its senses refer to that which is basic or to rules and standards.Principal is both a noun and an adjective. As a noun (aside from its specialized meanings in law and finance)it generally denotes a person who holds a high position or plays an important role:
Principal 和 principle 的意思完全不同，但常常被混淆。 Principle 仅仅是一个名词， 其主要意义指基本的东西或规则和标准。Principal 既是名词又是形容词。 作为名词（除了其在法律或财政金融上的特殊含义），它一般指居于高位或担任重要角色的人：
例句：
a meeting among all the principals in the transaction.
交易中重要人物的碰头会。

As an adjectiveit has the sense of .chief. or .leading..
作为形容词，它有.主要的.或.首要的.的意思