1. Nouns – gender
In Spanish, all nouns are either masculine or feminine, whether they denote a person, a thing, a place or an idea.
Masculine nouns usually end in -o: el libro, el curso, el colegio
Compound nouns (verb+noun) are always masculine: el cortaúñas, el rascacielos
Many nouns that end in –ma (those of Greek origin) are masculine: el problema, el tema, el sistema.
Exceptions to the rules include: la mano, la radio, la alarma, la pluma
Feminine nouns usually end in -a: la lengua, la casa, la escuela
Nouns that end in -ción, -sión, or -ía are feminine: la conversación, la televisión, la economía
So are the nouns ending in -dad, -tad, or -tud: la universidad, la amistad, la actitud…
…and those ending in -umbre or -za: la costumbre, la pobreza
Exceptions to the rules include: el día, el mapa, el sofá
Feminine nouns that begin with a stressed a or ha syllable use the masculine article in front of their singular forms, but the feminine article when in plural:
el agua, el aula, el alma, el área, el águila, el hacha, el hada
but
las aguas, las aulas, las almas, las áreas, las águilas, las hachas, las hadas
Some masculine nouns end in a consonant: el señor, el profesor
and they have a corresponding feminine form that ends in -a: la señora, la profesora.
Some nouns have the same masculine and feminine forms. In these cases, the article indicates the gender: el estudiante – la estudiante, el artista – la artista.
Finally, there are nouns that can be both masculine and feminine, but have a different meaning depending on gender:
el frente (front) – la frente (forehead)
el corte (cut) – la corte (court)
el pendiente (earring) – la pendiente (slope)