attoparsec

attoparsec

(unit, humour)About 31 mm (one inch). "atto-" is thestandard SI prefix for multiplication by 10^-18. A parsec(parallax-second) is 3.26 light-years; an attoparsec is thus3.26 * 10^-18 light years. Thus, one attoparsec permicrofortnight is about one inch per second.

This unit is reported to be in use (though probably not veryseriously) among hackers in the UK.