rachitisEnglishOxford New American Dictionaryrachitis /rəˈkīdəs, rəˈkaɪdəs / ▸ noun old-fashioned medical term for rickets. – DERIVATIVES rachitic /rəˈkidik, rəˈkɪdɪk / adjective– ORIGIN early 18th century: modern Latin, from Greek rhakhitis, from rhakhis ‘spine’.