An Etymological Dictionary of the German Language/Mark
Mark (1.), f., ‘marches, frontier,’ from MidHG. marc, ‘mark, token,’ OHG. marcha, f., ‘frontier, marches’; comp. OSax. marca, ‘territory,’ AS. mearc, f., ‘frontier, territory’ (E. march is not based on the AS. form, the c of which would not have changed to ch, but on OFr. marche, ‘frontier,’ which is of Teut. origin). To Goth. marka, f., ‘frontier,’ corresponds OIc. mǫrk, ‘wood,’ with a remarkable change of meaning; woods in Teut. times were often the natural boundaries between nations. The orig. meaning of the cognates of ‘frontier’ is supported by their primit. kinship with Lat. margo, ‘border,’ as well as by OIr. brú (from the prim. form *mrog), ‘border,’ Ir. bruig, W. and Corn. bro, ‘district, country, region,’ ModPers. marz, ‘frontier, marches.’ From Teut. are derived Ital. marca, Fr. marche, ‘frontier.’ See Mark (2) and Marke.
Mark (2.), f., ‘mark’ (coin), from MidHG. marc, marke, f., ‘mark, half a pound of silver or gold’; OHG. *marka (whence MidLat. marca, which first appears in documents in the latter half of the 9th cent.), AS. and MidE. marc, OIc. mǫrk, f., ‘mark, half a pound of silver.’ Its origin is obscure; the assumption that Marke, ‘designation, sign’ (with reference to the stamp), is a cognate, is not proved, since Mark orig. denoted a definite weight, and not a particular coin.
Mark (3.), n., from the equiv. MidHG. marc (gen. marges), n., ‘marrow, pith’; the MidHG. g has been preserved in mergeln; OHG. marg, marag, n., OSax. marg, n., Du. merg, n., AS. mearg, n., E. marrow, OIc. mergr, m., ‘marrow’; in this word r is due to Goth. z, according to the law of rhotacism; Goth. *mazga- is wanting. The latter points to pre-Teut. *mazgho-, to which OSlov. mozgŭ, m., Zend mazga, Sans. majjan, ‘marrow,’ all with a normal loss of the aspirate, correspond. The root is Sans. majj, ‘to immerse,’ to which Lat. mergere is allied.