noun. A data-processing error arising when the absolute value of a computed quantity is smaller than the limits of precision of the computing device, retaining at least one significant digit.

noun. The water which is now known to be often in transit beneath the apparently dry gravels of rivers in arid districts, such as the southwestern United States.

noun. A current flowing beneath the surface, or not in the same direction with the surface-current, over a certain region; an undercurrent: the opposite of surface-flow or surface-current.

noun. A condition in which the value of a computed quantity is smaller than the smallest non-zero value that can be physically stored; usually treated as an error condition

noun. The error condition that results from an attempt to retrieve an item from an empty stack

"The Arkansas River was always the primary source of water for both the North and South Side systems, although the North Side briefly flirted with using the 'underflow' of Fountain Creek."

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Triton  curiosky  denial-of-service  disputing  divineness