From The Free Dictionary.
brack·et (brkt) n.
a. A simple rigid structure in the shape of an L, one arm of which is fixed to a vertical surface, the other projecting horizontally to support a shelf or other weight.
b. A small shelf or shelves supported by such structures.
2. Architecture A decorative or weight-bearing structural unit, two sides of which form a right angle with one arm flush against a wall and the other flush beneath a projecting surface, such as eaves or a bay window.
3. A wall-anchored fixture for gas or electricity.
a. A square bracket.
b. An angle bracket.
5. Chiefly British One of a pair of parentheses.
6. A classification or grouping, especially within a sequence of numbers or grades, as a category of incomes sharing the same tax rate.
a. The distance between two impacting shells, the first aimed beyond a target and the second aimed short of it, used to determine the range for artillery fire.
b. The shells fired in such a manner.
tr.v. brack·et·ed, brack·et·ing, brack·ets
1. To furnish or support with a bracket or brackets.
2. To place within or as if within brackets.
3. To classify or group together.
4. To include or exclude by establishing specific boundaries.
5. To fire beyond and short of (a target) in order to determine artillery range.
See? Not a single mention of NCAA Basketball. Weird.
Even the Catholic Church decided a bracket pool would help in choosing the next Pope. It later became clear this method wasn't used when they went with Benedict XVI - a bad decision of Biblical proportions.