diffusion coefficient, $D$

Proportionality constant $D$ , relating the flux of amount of entities B to their concentration gradient $J n = − D ∇ c B$ .

Source:

Green Book, 2nd ed., p. 65

See also:

PAC, 1996, 68, 957 (Glossary of terms in quantities and units in Clinical Chemistry (IUPAC-IFCC Recommendations 1996)) on page 969