-itis

from The Collaborative International Dictionary of English v.0.48

-itis \-i"tis\ ([imac]"t[i^]s), [Gr. 'i`tis, orig, fem.
   adjective suffix.]
   A suffix used in medical terms to denote an inflammatory
   disease of; as, arthritis; bronchitis, phrenitis, nephritis.
   [1913 Webster]