Q From Shondra Tharp: I was looking up the word malacia and noticed that it was not only “softening of organs or tissue” but also “a craving for spicy foods”? Are these two meanings related in some way?
A The origin of both senses is Greek malakos, soft, a relative of malakia; the Oxford English Dictionary says this meant “softness, homosexual desire, sickness”, a splendid demonstration of how much cultural bias you can build into four words.
We borrowed malacia in the seventeenth century from the Latin version of the Greek word. The Oxford English Dictionary says that in Latin this meant a disorder of the stomach, especially the sickness and nausea that was suffered by pregnant women, but early writers in English took it to mean a craving for unnatural or unusual foods, a different symptom of pregnancy. Your second sense grew up only in the late nineteenth century and it would seem that in this case medical writers took the word directly from Greek, creating terms such as osteomalacia (softening of the bones) and gastromalacia (a softening of the lining of the stomach).
Incidentally, the combining form malaco- is also derived from the first of your meanings: it appears in malacoderm, used in zoology for an animal having a soft outer protective layer, as well as in a few other technical terms. Just to keep us all on our toes, malaco-, via another sense of the Greek original, can also refer to molluscs, as in malacology, their study.