In English, we have two ways to talk about nouns in a general sense. In normal speech, we say things like cats are vicious little creatures -- i.e. we use an indefinite plural. In some very formal prose, you'll see instead the cat is a vicious little creature --i.e. a definite singular.
The existence of the second is probably just a case of "translationese" -- it arises in lots of translations of Latin works, and I believe it is used that way in most of the modern Romance languages (French, Italian etc). Unfortunately this isn't easy for me to verify, as I have no idea whatsoever what to look for in the index of my grammar books.
Bizarrely, this fundamental (and straightforward) element of language seems to have been overlooked in the classical grammar models, so there is no common label for it (hence me not being able to look it up!). This means it is often overlooked in teaching, too. Many beginners' courses pass it by, and even when it comes up, you're not likely to get more than a little box-out mentioning it. It's not really "taught" in the same way as other grammar points. I suppose the reason for this goes back to the very basics of the structuralist view of grammar, which values form over meaning, and too often simply gives a few short sentences explaining usage after drilling form.
But we've been moving away from structuralism for quite some time now. The in-general/universal has been marooned by the incoming tide, as functional and communicative approaches have picked up on the link between form and meaning in the noun and article for specifical and truly indefinite cases, but they've not integrated the general/universal with it.
This underemphasis of the general/universal is particularly noticeable in Gaelic. It's not a subject I've seen come up often at all. I read it in one book and one book only, and I don't believe I've ever heard it discussed ever in classes. According to the book (well, my memory of it -- the book's 100 miles away), the general/universal in Gaelic is the definite singular. (The cat is a vicious little creature, the lion is a noble beast etc.) And yet....
When you study the genitive in Gaelic, it may be pointed out to you that while "describer nouns" in English always stay singular even when representing a plural concept (for example "biscuit" in "biscuit tin", "tooth" in "toothbrush"), this isn't the case in Gaelic genitives, which have both singular and plural forms.
So I was giving a talk in a classroom debate, and I mentioned "teenage pregnancy" which I rendered as "leatromach nan deugairean" -- "pregnancy [of] the teenagers". Genitive, plural. After the class, I started asking myself if that was right, thinking of the general/universal rule. Now I'm too confused and I'll just have to ask one of my teachers to try to clarify....