megohm

from WordNet (r) 3.0 (2006)

megohm
    n 1: a unit of resistance equal to one million ohms

from The Collaborative International Dictionary of English v.0.48

Megohm \Meg"ohm"\, n. [Mega- + ohm.] (Elec.)
   One of the larger measures of electrical resistance,
   amounting to one million ohms.
   [1913 Webster]