Tier
WordNet
noun
(1) One of two or more layers one atop another
"Tier upon tier of huge casks"
"A three-tier wedding cake"
(2) Something that is used for tying
"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
"Lumber of the highest grade"