1.) the smallest measurable unit that can be visibly seen
2.) the smallest measurable unit (about 0.001 femtometers)
3.) (Nautical, Nuclear) a quickly estimated unit of length equal to one hundred quadrillionth of a meter, often abbreviated as RHC when females or effeminate males are present.
Dammit! If I could only get that screw in another red cunt hair, this lid could seal!