How would you translate “the water is cold”?
It would be:
El agua está fría.
Do you see the problem? Why is it “el” and “fría”? If it’s “el”, shouldn’t it be “frío”? If it’s “fría”, shouldn’t it be “la”?
The explanation is quite simple: in Spanish, feminine nouns that start with a stressed “a” (or “ha”, since it’s the same thing phonetically) must be preceded by the masculine definite article (el) instead of the feminine one (la).
Where does this come from? It’s actually quite interesting: In Old Spanish, the feminine article was “ela”. What happens when you place “ela” before a noun that starts with a consonant?
The “e” tends to disappear. People would tend to pronounce it like this:
That’s what happened eventually, leading to the modern Spanish feminine definite article “la”. However, when you place “ela” before a noun that starts with a stressed “a” (or “ha”)…
…the “a” in “ela” tends to disappear, as it merges with the “a” of the noun:
This is where it comes from. So, we can say that we are really using a modified version of the Old Spanish feminine definite article and not the actual masculine definite article. It just happens to be the same thing. Interesting, isn’t it?
Here’s a list of feminine nouns that start with a stressed “a”:
Águila - Eagle
Alma - Soul
Aula - Classroom
Agua - Water
Área - Area
Arma - Weapon
Hacha - Axe
Hada - Fairy
Hambre - Hunger
if you use an adjective with any of these nouns, it should obviously be feminine:
El águila calva
El arma blanca