equ

Equ is a combining form and prefix in English that signals notions of equality, balance, or sameness. It is derived from the Latin aequus meaning equal and is used to form a wide range of words in different domains. In English, the morpheme often appears as equ- or equi-, with equi- used before vowels or certain consonants.

Etymology and usage: The equ- prefix comes from Latin aequus via Old French and later English. It appears in mathematical terms such as equation, equate, and equivalence, in measurements and shapes like equilateral or equidistant, and in general terms like equal, equality, and equity. The form equi- is a variant used before vowels or certain roots, as in equiangular, equinox, and equilateral. There are exceptions, however; not all words with equ- share the same root. For example, equine does not derive from the Latin aequus meaning equal but from equus meaning horse, illustrating a phonetic similarity rather than a semantic one.

Examples and domain usage: In mathematics and science, equ- words denote sameness or balance (equation, equilibrium, equivalent, equidistant). In everyday language, words such as equal, equality, and equity reflect the same root concept. In some specialized terms, equi- forms are used to indicate parity among components, such as equiangular or equinox.

See also: aequus, equi-, equ-, and related terms in etymology and nomenclature. Note that not every appearance of equ- in English carries the meaning of equality; context clarifies its origin.