base

BASE is an acronym that appears in several distinct contexts. The most widely recognized uses are BASE jumping, a sport involving parachuting from fixed objects, and the Bielefeld Academic Search Engine, a web search tool for academic repositories. The term is also encountered as the general word base in science and mathematics, and in various organization names that are not related to these uses.

BASE jumping derives its name from the four fixed objects from which jumps may be made: Building, Antenna, Span (bridge or gap), and Earth (cliff or natural surface). Participants deploy parachutes after leaping from these structures, typically at lower altitudes than typical skydiving. The activity is illegal or restricted in many locations and carries substantial risk, requiring specialized training, equipment, and awareness of wind, gear, and exit technique.

BASE, the Bielefeld Academic Search Engine, is a free web search tool designed to index and provide access to open-access academic documents. Operated by the Bibliotheksdienst der Universität Bielefeld, it harvests metadata and full texts from thousands of repositories and covers a broad range of disciplines. BASE emphasizes high-quality, openly accessible scholarly content and offers filtering by resource type, date, and license.

Other uses of BASE as an acronym appear in various technical, organizational, and regional names, and the term base remains common in chemistry, mathematics, and computer science, where it denotes a foundational concept rather than a fixed object in space.