epsilon
[see delta] 1. n. A small quantity of anything.
"The cost is epsilon." 2. adj. Very small, negligible; less than
marginal. "We can get this feature for epsilon cost."
3. `within epsilon of': close enough to be indistinguishable for
all practical purposes, even closer than being `within delta
of'. "That's not what I asked for, but it's within epsilon of
what I wanted." Alternatively, it may mean not close enough, but
very little is required to get it there: "My program is within
epsilon of working."