Base is the bottom part of something that supports or holds up the rest. A lamp has a base that keeps it steady on your desk. A statue stands on a base. Mountains rise from a base at ground level. In this sense, the base is literally what everything else rests on.

In baseball, a base is one of the four stations a runner must touch to score: first base, second base, third base, and home plate (though home plate is often just called home). Players run from base to base after hitting the ball, and a runner is safe when standing on a base.

The word also means a main location where operations happen. A military base is where soldiers live and work. When hiking in the mountains, base camp is where climbers set up their main camp before attempting the summit. Scientists in Antarctica work from research bases.

In chemistry and mathematics, base has specific technical meanings. A chemical base is a substance that neutralizes acids. In math, a base is the number that a counting system builds on: we use base 10 (counting by tens), while computers use base 2 (counting by twos, using only ones and zeros).

Base can also describe something low quality or morally wrong, like a base metal (common and inexpensive, unlike gold) or base behavior (selfish and dishonorable). This meaning is less common in everyday conversation.