<jargon> A quantity even smaller than epsilon, as small in comparison to epsilon as epsilon is to something normal; completely negligible. If you buy a supercomputer for a million dollars, the cost of the thousand-dollar terminal to go with it is epsilon, and the cost of the ten-dollar cable to connect them is epsilon squared.
Compare lost in the underflow, lost in the noise.
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Nearby terms: EPS « EPSILON « epsilon « epsilon squared » EPSIMONE » EPSS » EqL