What does «caballo» mean in Spanish?

Ungulate domestic mammal, of the equidae family, with a long mane and a tail covered with hair, used by humans for riding or as a draft animal.
Card that has the figure of a horse in the Spanish deck.
A chess piece that has the shape of a horse.
Support trestle used to support a timber when sawing.
Barren rock mass that cuts the lode.
Very strong and resistant person.
Large person, spiny.
Foolish, brutal person.
(a caballo) Mounted on a cavalry.
(a caballo regalado, no hay que mirarle el diente) Things that cost nothing can be admitted without inconvenience even if they have some defect.
(a mata caballo) Very hurriedly, in a hurry.
(caballo de batalla) Most debated topic in a discussion.
(caballo de batalla) Subject in which a person stands out.

Examples of use in Spanish: "la filosofía es su caballo de batalla"
(caballo de batalla) Main point.
(Caballo de Troya) Gigantic wooden horse inside which the Greeks hid to take the city of Troy.
(caballo de Troya) Dangerous gift.
(caballo de vapor) Unit of power (symbol CV) corresponding to 75 kilograms per second.