tier

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. One of a series of rows placed one above another: a stadium with four tiers of seats.
2. n. A rank or class.
3. v. To arrange (something) into or rise in tiers: tier a wedding cake; balconies that tier upward.
4. n. One that ties: a tier of knots.

Century Dictionary and Cyclopedia

1. n. A range of mountains.
2. n. One who or that which ties.
3. n. A child's apron. Also, erroneously, tire.
4. n. In entomology, same as leaf-tier.
5. n. A row; a rank, particularly when two or more rows are placed one above another: as, a tier of seats in a theater; the old three-decked war-ships had three tiers of guns on each side, the upper, middle, and lower tiers.
6. n. In organ-building, same as rank, 1 .
7. To pile, build, or arrange in tiers. Compare tierer.
8. n. See tire.

Wiktionary

1. n. One who ties (knots, etc).
2. n. Something that ties.
3. n. A layer or rank, especially of seats or a wedding cake.
4. v. transitive To arrange in layers.
5. v. transitive To cascade in an overlapping sequence.

GNU Webster's 1913

1. n. One who, or that which, ties.
2. n. A chold's apron covering the upper part of the body, and tied with tape or cord; a pinafore.
3. n. A row or rank, especially one of two or more rows placed one above, or higher than, another.

WordNet 3.0

1. n. a relative position or degree of value in a graded group
2. n. a worker who ties something
3. n. any one of two or more competitors who tie one another
4. n. something that is used for tying
5. n. one of two or more layers one atop another