third base

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

• noun The third of the bases on the diamond counterclockwise from home plate; the last base to be reached by a runner before home plate.
• noun The position played by the third baseman.

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

• noun baseball The base after second base in a counter-clockwise path around a baseball infield.
• noun colloquial Touching a man's or woman's genitals in a sexual manner; mutual masturbation.

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

• noun the base that must be touched third by a base runner in baseball
• noun the fielding position of the player on a baseball team who is stationed near the third of the bases in the infield (counting counterclockwise from home plate)