名词
1. 一排;一行;一列
A tier is a row or layer of something that has other layers above or below it.
2. (组织或系统的)层，级
A tier is a level in an organization or system.
1. one of two or more layers one atop another
e.g. tier upon tier of huge casks
a three-tier wedding cake
2. something that is used for tying
e.g. the sail is fastened to the yard with tiers
3. a worker who ties something
Synonym: tier up
4. any one of two or more competitors who tie one another
5. a relative position or degree of value in a graded group
e.g. lumber of the highest grade