What is Gender anyways? It's a grammatical term used when a language groups nouns
and adjectives into different classes, ie masculine and feminine.
In Spanish we run into a minor problem with this grouping of nouns and adjectives.
Sometimes there is not a general consensus as to the gender of certain words! First
let's look at many common words. We already know that almost always a masculine word
ends in o or e and a feminine word ends in a. For example
niño - niña
oso - osa
esposo - esposa
perro - perra
director - directora
In some cases there are totally different words that are used to designate
masculine or feminine, such as:
hombre - mujer
toro - vaca
macho - hembra
Now we come to a group or class of words that are interchangeable regardless of sex.
These words don't change, whether or not they are referring to a man or a woman
el dentista - la dentista (dentist)
el periodista - la periodista (newspaper reporter)
el artista - la artista (artist) (and almost all the words ending in -ista)
el testigo - la testigo (witness)
el intérprete - la intérprete (interpreter)
And finally we come to a group of words that I mentioned in the opening paragraph.
These words can't decide if they want to be masculine or feminine. Or the speakers
of Spanish can't decide.
el or la mar (sea)
el or la azúcar (sugar)
el or la calor (heat)
el or la puente (bridge)
And there are a few others that change their meaning based on if they are masculine
or feminine.
el cólera (cholera sickness) - la cólera (anger)
el clave (claves musical instrument) - la clave (key or code)
el capital (capital money) - la capital (capital city)