iron-gray
‘a dark gray with a slightly greenish tinge’
Lexical development traced from the Tamil root:
O.E. isengræg < < M.E. iron < O.E. iren variant (with rhotacism of -s-) of isen < Proto-G. isarn < Ce. isarnon + gray < is-(e)ro ‘powerful, holy’ < ai < eis < Tamil irumpu