precursor

A precursor is something that precedes another in time, development, or function. In everyday use, a precursor is an antecedent or forerunner of something later. The term derives from Latin praecursor, meaning forerunner or preceder.

In science and industry, a precursor often refers to a chemical compound that participates in or is transformed to form a target compound. Precursors are used in synthesis and manufacturing, and they may be regulated because they can be misused to produce controlled substances or hazardous materials.

In biology and medicine, a precursor can describe a cell or tissue that has the potential to differentiate into a more specialized form, known as a precursor cell or progenitor cell. Precursors are important in development, tissue repair, and metabolic pathways, where precursor molecules contribute to the production of larger biomolecules such as nucleotides, amino acids, or lipids.

In technology and history, precursors denote earlier devices, ideas, or structures from which later innovations arose. For example, early forms of communication and data storage are considered precursors to more advanced telecommunication systems and digital technologies. The term also appears in broader cultural contexts to describe early indicators or signals of subsequent change.