The last lesson ended with a rule that is right for 1,866 of 1,887 nouns. This lesson is about the nouns that rule cannot be scored on, because they have no plural to compare with.
The word list has 683 words that are only nouns. Of these, 75 have no plural that the list records and the dictionary confirms. That is the list printed in the lab, in the order of the alphabet.
What the list is made of
Read it once from the top. Most of it is things you do not count. Advice, assistance, clothing, equipment, furniture, information, knowledge, money, software, wealth: each names a mass of something, and in each case you count it with a phrase such as a piece of or some. Happiness, darkness, poverty, violence and tennis are the same: you have a lot of them or a little.
A smaller group of nine already looks plural or does not change: news, series, sheep, species, aircraft, data, politics, mathematics, and personnel, which names a group of people and is used as a plural. News takes a singular verb, and series and sheep are the same for one and for many.
What such a noun never takes
It never takes -s. It does not take a or an. And it goes with much and a little, not many and a few. The lab counts nothing about these, because the printed list holds no sentences. The count for a and an comes from a whole novel, which no page can carry, and it is marked quoted where it appears.
The two kinds that are limits of the list
Sixteen of the 75 are the names of days and months. They are here because the word list records only the singular name, and yet two Mondays is correct English. So for them the rule “never takes -s” is false. Do not carry the rule over to them.
Three more need care. Basis has the plural bases, which the word list does not record. Hell and sake live in fixed phrases, and the dictionary confirms no plural for either, so they are on the list rightly and teach you little. The list is not a list of nouns that cannot have a plural; it is a list of nouns where the word list records none. Read it that way.
Words that are not on it
The lab can also show the words that were set aside before the count. A program that sorts words by their use calls some small words nouns, such as and, at and he. They are not nouns here, and each is listed with the reason it was taken out.