1
: the base that must be touched third by a base runner in baseball
2
: the player position for defending the area around third base
3
slang + impolite
: amorous touching or caressing especially of the genitals
—usually used in phrases like get to third base or reach third base
One boy told everyone he got to third base with her when she didn't even know what counted as third base, but unless it was French-kissing, he hadn't.—Meryl Wilsner
compare first base sense 4, home base sense 3, second base sense 3
third baseman
noun
: the baseball player stationed at the third-base position
Cite this Entry
“Third base.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/third%20base. Accessed 2 Sep. 2026.
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