hept

Hept is a combining form meaning seven, used in scientific terminology to denote seven units or components. It derives from the Greek prefix hepta- and appears across disciplines, especially in chemistry, geometry, and biology.

In chemistry, hept- forms the basis for names of seven-carbon structures and related compounds. Examples include heptane, a seven-carbon alkane; heptene, a seven-carbon alkene; and heptanol, a seven-carbon alcohol. The prefix also appears in various biomolecules and derivatives that feature a seven-carbon backbone or chain.

In mathematics and geometry, seven-sided figures and related concepts use the term hept. A seven-sided polygon is called a heptagon, and a seven-pointed star is a heptagram. Heptagonal numbers describe figurate numbers associated with sevenfold symmetry.

In biology and biochemistry, the term appears in several contexts. A heptose is a seven-carbon monosaccharide. The noun heptad refers to a group or pattern of seven components, such as a seven-residue repeat in certain protein structures.

The form hepta- is also encountered in word formation, often before vowels, while in many compound terms the shorter form hept- is preferred, as in heptane or heptagon. Overall, hept serves as a versatile root in technical vocabulary to signal the number seven.