Deca

Deca, deka-, or deca- is a decimal prefix in the metric system indicating a factor of ten. In the International System of Units (SI), the official prefix is deka- with the symbol da. It derives from the Greek deka, meaning ten. The prefix appears in names of units such as decameter (dam), decagram (dag), and decaliter (dal). Although valid, deca- prefixes are less common in everyday use, with kilo- and higher prefixes more widely encountered.

DECA, Inc. is an international student organization focused on business, marketing, entrepreneurship, and leadership. It was founded in 1946 as the Distributive Education Clubs of America. The organization expanded to include members from high schools and colleges around the world and operates a competitive events program, along with leadership conferences and career development activities. The name is now used as a brand identity for the organization, which maintains DECA chapters in various educational institutions.

In science and mathematics, deca appears in terms describing tenfold structures or quantities. For example, decamer denotes a complex composed of ten subunits, a usage that appears in biochemistry and molecular biology. The prefix also appears in other historical or specialized terms, though such uses are comparatively rare outside specific fields.