tier
     n 1: a relative position or degree of value in a graded group;
          "lumber of the highest grade" [syn: {grade}, {level}]
     2: any one of two or more competitors who tie one another
     3: a worker who ties something [syn: {tier up}]
     4: something that is used for tying; "the sail is fastened to
        the yard with tiers"
     5: one of two or more layers one atop another; "tier upon tier
        of huge casks"; "a three-tier wedding cake"
Source: WordNet® 2.0