OED2 gives the Gk. enantiodromia (englished, of course), running in contrary ways;
from enantios + dromos (opposite + running).

and here's where I got the notion:
http://www.users.bigpond.com/burnside/contradicting.htm

Burnside differentiates between a word which shows "historical drift" (enantiodromic) and one which "maintains... two opposite meanings side by side", which he characterizes as a Janus word or amphibolous.