12-12. noun, nouns.
[X is a noun.] = X is a kind of word. When people hear this kind of word, they know what person or place or kind of thing you are saying something about.
[The words "animal" and "machine" are nouns.]
12-13. add, adds, to add, adding, added.
[You add something.] = You put something more in a place.
[You add J and K.] = J and K are numbers, and you want to know this other number: If the number of things inside a group was J before, and then the number of things you put into the group is K, you do something with the numbers J and K to know the number of things inside the group now.
[There were four eggs inside this container, then I added three more eggs, and now there are seven eggs inside the container.]
12-14. sharp.
[X is sharp.] = X has a thin side or narrow end that can easily cut things or make holes in things.
[You need to be careful when you use these metal things because they are very sharp.]
12-15. dangerous.
[X is dangerous.] = X is able or likely to hurt someone or cause someone to die.
[When you are using a vehicle, drinking alcohol is dangerous.]
Many nouns can change to show the number of things.
Some nouns change like this:
If you see one thing, you say: "I see one person. I see one child. I see one man. I see one woman."
If you see more than one, you say: "I see two people. I see three children. I see many men. I see many women."
Often the first part of the noun does not change, but you add "-s" after the noun to show there is more than one, like this:
If you see one thing, you say: "I see one cat. I see one bird. I see one animal."
If you see more than one, you say: "I see four cats. I see five birds. I see __________."