scoliosis n.

curvature of the spine, 1704, Modern Latin, from Greek lordosis, from lordos "bent backwards," a word of uncertain origin, with possible cognates in Armenian, Celtic, and Germanic. From 1941 in reference to the mating position assumed by some female mammals. Related: Lordotic.

"having two equal sides," 1550s, from Late Latin isosceles, from Greek isoskeles "with equal legs; isosceles; that can be divided into two equal parts," from isos "equal, identical" (see iso-) + skelos "leg," from PIE *skel-es-, from root *skel- "bend, curve" (see scoliosis).