Sometimes we can use countable nouns in a general context with a definite rather than indefinite article to create a sense of the thing as a category. For example, 'The computer has transformed modern life.' Here 'computer' is not being used as a countable noun, but rather the definite article implies that we are talking about it as a general category. Is there a name in grammar for this exception to the normal rules on how we choose articles for nouns?
I've heard it called the 'generic definite article', but I'm not certain there is a name for the use as such because it isn't really an 'exception' to the use of the definite article when you understand what the noun represents.
In English we commonly use a singular noun to represent a class of objects - eg 'the deer' to mean all deers. Because the class is a specific, unique thing, it follows that it is used with the definite article. Likewise, 'the computer' is a generic term for a wide range of computing devices. Saying 'the computer' instead of 'computers' can be a stylistic choice, but what the term means today is very different from what it meant to Charles Babbage in the 1800s, and saying, for example, "the history of the computer" may better acknowledge everything that falls under the term than saying 'computers'.