rachitis

Unadapted borrowing from New Latin rachitis, used by the British physician Francis Glisson (1597–1677) to refer to rickets, from Koine Greek ῥαχῖτις (rhakhîtis) (in ῥαχῖτις νόσος (rhakhîtis nósos, “spinal inflammation”, literally “spinal disease”)), the feminine form of ῥαχίτης (rhakhítēs, “in or of the spine, spinal”), from Ancient Greek ῥάχῐς (rhákhĭs, “lower part of the back; (anatomy) backbone, spine”) (probably ultimately Pre-Greek) + -ῖτις (-îtis) (feminine form of -ῑ́της (-ī́tēs, suffix forming nouns with the sense ‘one connected to’)). By surface analysis, rach- + -itis.

来源：wiktionary