/frak"tl/ , n. Math., Physics.
a geometrical or physical structure having an irregular or fragmented shape at all scales of measurement between a greatest and smallest scale such that certain mathematical or physical properties of the structure, as the perimeter of a curve or the flow rate in a porous medium, behave as if the dimensions of the structure (fractal dimensions) are greater than the spatial dimensions.
[ fractale, equiv. to L fract ( us ) broken, uneven (see FRACTUS) + -ale -AL 2 ; term introduced by French mathematician Benoit Mandelbrot (born 1924) in 1975 ]