ῥάχις

A. the lower part of the back, the chine, συὸς ῥ. Il. 9.208.

2. spine or backbone, σύγκειται ἡ ῥ. ἐκ σφονδύλων, τείνει δ’ ἀπὸ τῆς κεφαλῆς μέχρι πρὸς τὰ ἰσχία Arist. HA 516a11, cf. PA 654b12, al.; ὑπὸ ῥάχιν παγέντες impaled, A. Eu. 190, cf. S. Fr. 20, E. Cyc. 643; μυελὸς κοίλης ῥάχεως Archel. ap. Antig. Mir. 89, cf. Pl. Ti. 77d, 91a.

II. anything ridged like the backbone:

1. ridge of a hill or mountain, Hdt. 3.54, 7.216, IG 42(1).71.14 (Epid., iii B.C.), Plb. 3.101.2, D.H. 5.44, Str. 3.2.3 (pl.); ἂν ῥάχιν along the ridge, GDI 5075.69 (Crete, i B.C.); so Archil. 21 like ned Thasos to an ὄνου ῥάχις.

2. ῥ. ῥινός bridge of the nose, Poll. 2.79, Ruf. Onom. 35.

3. ῥ. φύλλου mid-rib of a leaf, Thphr. HP 3.7.5, al.

4. the sharp projection on the middle of the shoulder-blade, Gal. UP 13.10, Ruf. Onom. 71.

5. outer edge of the arm of the polypus, Arist. HA 524a7.

6. trunk, of Dagon, LXX 1 Ki. 5.4.