Read the dictionary definition of tier. All definitions for this word.
1. one of two or more layers one atop another
1. tier upon tier of huge casks
2. a three-tier wedding cake
2. something that is used for tying
1. the sail is fastened to the yard with tiers
3. a worker who ties something
4. any one of two or more competitors who tie one another
5. a relative position or degree of value in a graded group
1. lumber of the highest grade