An Etymological Dictionary of the German Language/Backe
Backe (1.), Backen, m., especially used in the compounds with Asch-, Hinter-, hence the lit. meaning, ‘buttock.’ The correct HG. form, which has the regular permutation of k to ch, is seen in MidHG. bache, OHG. bahho, ‘ham, flitch of bacon’ (yet MidHG. also ars-backe, m.), which as ‘bacon’ made its way into OFr., and thence into Eng. also. Although it has been connected by the linguistic instinct of ModHG. with the following word, they are not allied; it is more probable that Backe and the stem bak, discussed under Backbord, is most closely connected with it.
Backe (2.), m., f., also Backen, m. (the latter espec. in the compounds Backenzahn, -streich), ‘cheek’; from MidHG. backe, m., ‘jaw, jawbone, cheek.’ OHG. has the doublets baccho (whence the MidHG. and ModHG. ck) and bahho, which produce MidHG. bache. Comp. MidHG. kinnebache beside kinnebacke, which compound too, even in OHG. (as chinni-bahho), is more frequent than the simple word; comp. OSax. kinni-bako, Du. kinnebakken. It is still uncertain whether Lat. bucca, ‘cheek,’ is allied to it; its initial b might have arisen from bh, as in barba (see Bart); but the two differ in meaning; while the Lat. signifies ‘the inflated cheek,’ the G. word orig. denoted ‘jaw.’