dichotome

Dichotome is an adjective meaning divided into two parts or two-part in form or function. The noun form can refer to a dichotomous structure or process that exhibits such a two-way division. Etymology traces to Greek di- “two” and temnein “to cut,” passing through Latin and French into English.

In biology and botany, dichotomous (or dichotome) branching describes a growth pattern in which an axis repeatedly splits into two branches of comparable size. This mode of development is observed in various plant lineages and in some fungi, and it contrasts with lateral or single-point branching.

In taxonomy and identification, the term relates to the broader concept of dichotomy. A common application is the dichotomous key, a tool that presents two mutually exclusive alternatives at each step to guide users toward a correct identification of a specimen. Although the standard term is “dichotomous key,” some texts may refer to the underlying principle as dichotome in describing two-way decision points or classifications.

In philosophy and logic, dichotome usage likewise describes binary, two-part classifications or distinctions, emphasizing the split into opposing categories rather than more nuanced spectra.

See also: dichotomy, dichotomous, dichotomous key, dichotomous branching.

Note: While dichotomous (two-part) is the more widely used English form in many disciplines, dichotome appears in some texts as a variant or in fields emphasizing two-way division.