goalpost

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One of a pair of posts usually joined with a crossbar to form a goal, as in soccer or ice hockey.
• noun A post or a pair of posts supporting a crossbar and either supporting or extending into the uprights of a goal, as in football.

from The Century Dictionary.

• noun One of the upright posts forming one side of the goal. See goal, 2.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Sport) One of two posts supporting a crossbar which forms a goal{3}, especially in American football; also, in football the entire structure consisting of the posts, crossbar, and two uprights. To score a goal by kicking the football, the ball must pass above the crossbar and between the vertical lines formed by the uprights.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun sports In American football, the tall Y-shaped upright, now usually of fiberglass, at either end of the playing field, through which a football must go in order to score a field goal. Originally, they were H-shaped, with two wooden posts on either side.
• noun sports One of the two side poles of the goal.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun one of a pair of posts (usually joined by a crossbar) that are set up as a goal at each end of a playing field