How do you spell Tier

Available Definitions:
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)  v. t. - A row or rank, especially one of two or more rows placed one above, or higher than, another; as, a tier of seats in a theater.