What is the X in X-mas?
1839, "illness without a specific cause," earlier (1660s) "depression or melancholy without real cause," earlier still (late 14c.) ipocondrie "upper abdomen," from Late Latin hypochondria "the abdomen," from Greek hypokhondria (neuter plural of hypokhondrios), from hypo- "under" (see sub-) + khondros "cartilage" (of the breastbone); see grind (v.). Reflecting ancient belief that the viscera of the hypochondria were the seat of melancholy and the source of the vapors that caused such feelings.
hypochondria hy·po·chon·dri·a (hī'pə-kŏn'drē-ə)
The neurotic conviction that one is or is likely to become ill, often involving experiences of pain when illness is neither present nor likely. Also called hypochondriasis.
hypochondrium hy·po·chon·dri·um (hī'pə-kŏn'drē-əm)
n. pl. hy·po·chon·dri·a (-drē-ə)
The upper lateral region of the abdomen on either side of the epigastrium and below the lower ribs.