A property of 
is said to hold almost everywhere if the set of points in
where this property fails is contained
in a set that has measure zero.
Almost Everywhere
See also
Almost Everywhere Convergence, Almost Surely, Measure ZeroExplore with Wolfram|Alpha
References
Jeffreys, H. and Jeffreys, B. S. "'Measure Zero': 'Almost Everywhere.' " §1.1013 in Methods of Mathematical Physics, 3rd ed. Cambridge, England: Cambridge University Press, pp. 29-30, 1988.Sansone, G. Orthogonal Functions, rev. English ed. New York: Dover, p. 1, 1991.Referenced on Wolfram|Alpha
Almost EverywhereCite this as:
Weisstein, Eric W. "Almost Everywhere." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/AlmostEverywhere.html