Stephan> > "(nautical mile), ang (Angstrom), parse, lightyear"
Stephan> >
Stephan> > parse or parsec ?
Stephan> 
Stephan> I would say "parsec" since it's an astronomical unit like "lightyear".
Correct. But I think you shouldn't translate it directly, just put the
description within bracket, like "parsec(parallax second)".

parsec=parallax second
A unit of astronomical length based on the distance from Earth at which
stellar parallax is one second of arc and equal to 3.258 light-years,
3.08610 kilometers, or 1.91810 miles.