In mathematics, base refers to:
In chemistry, a base is the reactive complement to an acid. (Sometimes the term alkali has been used historically where base is now preferred.) See Acid-base reaction theories. Technically, a substance capable of neutralizing acid, with a pH greater than 7.0.
In biochemistry, see nitrogenous base.
In baseball, a base is one of 4 bags placed at corners of the infield diamond that a player has to run to after hitting the ball.
In a transistor the base is the controlling connection to the junction[?].
The name of the terrorist group Al-Qaida translates as "the base."
In 2001, the catchphrase "All your base are belong to us" swept across the Internet. It came from a poorly translated video game called Zero Wing.
BASE jumping is a popular variation on skydiving.