A Random Number which lies within a specified range (which can, without loss of generality, be taken as [0, 1]), with a Uniform Distribution.
References
Press, W. H.; Flannery, B. P.; Teukolsky, S. A.; and Vetterling, W. T. ``Uniform Deviates.'' §7.1 in
Numerical Recipes in FORTRAN: The Art of Scientific Computing, 2nd ed. Cambridge, England:
Cambridge University Press, pp. 267-277, 1992.