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3.
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!
by NeightR March 08, 2006
 
1.
Standard unit of measurement for nearly infinitesimal distances.
"Holy shit, that speeding car missed me by a red cunt hair."
by Sakure April 07, 2003
 
2.
A unit of measurement favored by old-school southern carpenters and general contractors.
CARPENTER 1:"Say fella...would you step back n' take a look at
n'see how this door fits?"

CARPENTER 2:"Hmmm...'bout a coupla RED CUNT HAIRS off the
bottom oughta' do it.Break out the sander."
by L.MARTIN September 27, 2005
 
4.
This term denotes an even smaller measurement than a cunthair
Its a little too big, just take a Red cunthair off it.
by Englethrope B Squeebe December 28, 2007