A number that is raised to a power, or base of an exponential function. This finds common use, for example, in the depiction of numbers, for instance, 10 is the base used in the decimal system, whereas 2 is the base in the binary system. See also numeral system and radix
In topology, a base (topology) for a topology is a set of open sets such that every element of the topology is a union of the base sets. See also subbase.
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.
In Marxism describes the material equipment and material relations of human society, as distinct from the 'superstructural' forms of society - laws, customs, ideas, beliefs, etc.
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. See Table of bases
Base is also an isolated settlement in inhospitable conditions that must rely on outide help in order to survive, such as military base, Antarctica base, Moon base.