In spanish what are most nouns ending in o and OS?

In Spanish, nouns ending in -o are typically masculine, while nouns ending in -os are typically masculine plurals.

Here are some examples:

Masculine singular nouns ending in -o:

* libro (book)

* gato (cat)

* río (river)

* árbol (tree)

* coche (car)

* amigo (friend)

Masculine plural nouns ending in -os:

* libros (books)

* gatos (cats)

* ríos (rivers)

* árboles (trees)

* coches (cars)

* amigos (friends)

However, there are exceptions to this rule:

Feminine nouns ending in -o:

* mano (hand)

* foto (photo)

* radio (radio)

* moto (motorcycle)

Feminine nouns ending in -os:

* altos (highs)

* ceros (zeros)

* ojos (eyes)

Nouns ending in -o that can be either masculine or feminine:

* el/la testigo (witness)

* el/la agente (agent)

It's important to note that the gender of a noun is not always determined by its ending. There are many nouns that do not follow these general rules. It is always best to consult a dictionary or grammar book if you are unsure about the gender of a noun.