What do (O.E.), (general W.Gmc.), and (cf. M.Du) mean in etymology?

I looked up -ness at a href="http://www.etymonline.com/" rel="nofollow"http://www.etymonline.com//a and it said: suffix of action, quality or state, attached to an adj. or pp. to form a noun, from O.E. -nes(s), general W.Gmc., cf. M.Du. -nisse, O.H.G. -nissa, Ger. -nis, Goth. -inus. I was wondering what the abbreviations in parentheses in my question mean. Thanks for taking the time to answer!