Dear N:

You wrote:

Could one say, as far as grammar is concerned, “the disease of the common cold” instead of “the disease
which is the common cold”, in the same way one can say “the disease of malaria”?

I know that normally one would just say “common cold”, but I want to know if “the disease of the common cold”
is grammatically possible. If it is not, is it because we have the definite article and we say “THE common cold”?

No one would ever say it. The common cold is not a disease by most people. The word “disease” implies a certain severity. At worst, the common cold would be an illness, but a minor one at that.

For the sake of argument, let us assume that the common cold would be considered a disease. One would still not say “the disease of the common cold.” With the article “the,” there is a sense of specificity. In other words, “the common cold” is something specific. But “disease” is already specific and you are talking about the same thing. You would not use a second “the,” and very rarely does anyone use “common cold” without “the.”

Perhaps I can illustrate another instance. There is a difference between these two phrases:
1. The condition of pregnancy
2. The condition of the pregnancy

(Keeping with the medical imagery) #1 is describing a certain condition called “pregnancy.” It is general. It refers to a specific condition called pregnancy–just as the one example you gave referred to a disease called malaria. The condition is specific, but the pregnancy is not. You are just referring the state that women sometimes find themselves in.

If I were to ask someone, “What is the condition of pregnancy?” I would be asking, in effect, for a definition because “pregnancy” is not specific. I would expect an answer of something like, “Pregnancy is a condition of a female which…” etc.

However, #2 refers the specific condition of a specific pregnancy. I have a friend whose daughter is expecting a baby this week. I might ask her, “What is the condition of the pregnancy?” I am referring to the specific pregnancy of her daughter. I would be asking how her daughter’s pregnancy is coming along. I would be expecting an answer telling me how her daughter is feeling or if there are any signs of the baby coming forth.

I hope this helps. You rightly noted that the “the” does make a difference.