gradation

Gradation is the process or result of a gradual change from one state, degree, or level to another. The term, from Latin gradus, is used across disciplines to describe continuity and a spectrum rather than discrete boundaries. In art and color theory, gradation denotes smooth transitions of light, shade, or hue, as seen in shading techniques or color ramps used in painting, photography, and digital graphics. In design and visualization, gradients enable subtle variation and can convey depth or movement.

In education and quality assessment, gradation refers to ordered levels within a scale, such as grades, severity levels, or ranked categories. A gradual progression, rather than a single cutoff, helps reflect differences in performance, risk, or condition.

In biology and anthropology, gradation describes continuous variation among individuals or populations along a cline. Rather than separate species or categories, traits may exist on a spectrum, with gradual shifts in frequency or expression. In linguistics, gradation historically referred to alternations within related word forms, notably ablaut gradation in Proto-Germanic and related languages, where vowels change across strong and weak verb forms.

In practical contexts, gradation contrasts with abrupt change or discrete steps, though real-world systems often approximate either. Gradation is also used in geology, materials science, and other fields to discuss gradual transitions in texture, composition, or properties.