continuum
/kənˈtɪnjʊəm/
noun
a continuous sequence in which adjacent elements are not perceptibly different from each other, but the extremes are quite distinct.
"a continuum of special educational needs"
A continuum is something that keeps on going, changing slowly over time, like the continuum of the four seasons. In addition to meaning "a whole made up of many parts," continuum, pronounced "kon-TIN-yoo-um," can describe a range that is always present.

