1
- a set or category of things having some property or attribute in common and differentiated from others by kind, type, or quality等级; 种类, 品种：
it was good accommodation for a hotel of this class
对这一等级的旅馆来说, 膳宿已经是很好的了
a new class of heart drug.
一类心脏病新药。
1.1
- Biology a principal taxonomic grouping that ranks above order and below phylum or division, such as Mammalia or Insecta【生】纲（目之上, 门之下, 如哺乳纲, 昆虫纲）。
1.2
- Brit. a division of candidates according to merit in a university examination〈英〉（大学考试成绩的）等级：
he received a third class in literae humaniores.
他人文科学成绩得了三等。
2
- mass noun the system of ordering a society in which people are divided into sets based on perceived social or economic status（根据公认的社会地位、经济地位划分的）社会等级：
people who are socially disenfranchised by class
被社会等级剥夺了社会权利的人们
as modifier the class system.等级制度。
2.1
- count noun a set in a society ordered in such a way社会阶级, 阶层：
the ruling class.
统治阶级。
2.2
the classes
archaic the rich or educated〈古〉富人; 受过教育的人。
2.3
- informal impressive stylishness in appearance or behaviour〈非正式〉（外表、举止的）风度, 气质, 高格调, 高品位：
she's got class - she looks like a princess.
她很有气质——像个公主。
3
- a group of students or pupils who are taught together班, 班级。
3.1
- an occasion when pupils meet with their teacher for instruction; a lesson课：
I was late for a class.
我上课迟到了。
3.2
- a course of instruction课程：
I took classes in Indian music.
我参加了印度音乐课程的学习。
3.3
- N. Amer. all of the college or school students of a particular year〈北美〉同届（大）学生：
the class of 1907.
1907级学生。
with obj.(常作be classed as)
- assign or regard as belonging to a particular category把…分类, 将…归类：
conduct which is classed as criminal.
类属犯罪的行为。
短语
class A（或B, C）drug
- an illegal narcotic drug classified as being of the most harmful and addictive (or a less harmful and addictive) kind, possession or sale of which incurs corresponding legal penalties.A(或B, C)类毒品（根据其有害程度和上瘾程度划分为A, B或C类的某种毒品, 私藏或出售将导致相应的法律处罚）。
class act
- chiefly N. Amer. a person or thing displaying impressive and stylish excellence〈主北美〉出类拔萃的人, 气质超群的人, 出色的事物。
in a class of（或on）its（或one's）own
- unequalled, especially in excellence or performance（尤指优秀品质、表现）无与伦比的, 独一无二的, 独具一格的。
词源
mid 16th cent. (in sense 3)： from Latin classis'a division of the Roman people, a grade, or a class of pupils'.