Identifying Reverse-Gender Nouns in Spanish
Although the gender of most Spanish nouns is fairly obvious (nouns that end in -o often are masculine, and nouns that end in -a often are feminine), some Spanish nouns reverse their gender. These reverse-gender nouns can be quite tricky — unless of course you know to watch for them.
True reverse-gender Spanish nouns
Some nouns that end in -eta and -ma (words that are derived from the Greek language) are masculine, as are the words el día (the day) and el mapa (the map). El planeta (the planet) is the trickster reverse-gender noun that ends in -eta. Following are the deceptively masculine words that end in -ma:
el clima (the climate)
el drama (the drama)
el idioma (the language)
el poema (the poem)
el problema (the problem)
el programa (the program)
el sistema (the system)
el telegrama (the telegram)
el tema (the theme)
Here are a couple nouns that end in -o that are feminine:
la mano (the hand)
la radio (the radio)
Special gender considerations
To prevent the clash of two vowel sounds, the Spanish language uses the masculine singular article el (un) with feminine singular nouns that begin with a stressed a sound (a- or ha-). In the plural, you use las (unas) for these nouns. EVen though, in the singular, they look like masculine nouns, they really are feminine nouns.
Commonly used words with this designation include el agua (the water) and las aguas (the waters); un alma (a soul) and unas almas (some souls); and el ave (the bird) and las aves (the birds).
And don't be fooled by abbreviations. La foto is the abbreviation for la fotografía (the photograph), and la moto is the abbreviation for la motocicleta (the motorcycle).