-o/-a

Noun Gender Markers

Foundations

Spanish nouns are either masculine (often ending in -o) or feminine (often ending in -a). This 'gender' affects the articles and adjectives used with the noun.

How It Works

In Spanish, every noun is classified as either masculine or feminine. This is called grammatical gender. It's a fundamental concept because other words in the sentence must 'agree' with the noun's gender.

The most common and helpful rule of thumb is:

  • Nouns ending in -o are usually masculine.
  • Nouns ending in -a are usually feminine.

Why is this important?
The gender of a noun determines the form of the words that describe it, such as articles and adjectives. For example:

  • You use 'el' (the) with masculine nouns and 'la' with feminine nouns. See definite articles for more.
  • Adjectives must also change their endings to match the noun's gender. See adjective agreement for details.

This pattern is a great starting point, but be aware that there are other noun endings and some common exceptions to this rule (like 'el problema' or 'la mano'). For now, focus on recognizing this main -o/-a pattern.

Examples (4)

  1. el libro

    the book

    Word by Word: the book

    'Libro' ends in -o, so it is a masculine noun and uses the masculine article 'el'.

  2. la casa

    the house

    Word by Word: the house

    'Casa' ends in -a, so it is a feminine noun and uses the feminine article 'la'.

  3. un gato negro

    a black cat

    Word by Word: a cat black

    'Gato' is masculine, so the indefinite article 'un' and the adjective 'negro' are also in their masculine forms.

  4. una mesa alta

    a tall table

    Word by Word: a table tall

    'Mesa' is feminine, so the indefinite article 'una' and the adjective 'alta' are also in their feminine forms.

Common Mistakes

  • Assuming the -o/-a rule has no exceptions.

    la problema
    el problema

    While the -o/-a rule is a great guide, some common nouns are exceptions. For example, 'problema' and 'mapa' end in -a but are masculine. You'll learn these exceptions over time.

  • Forgetting that articles and adjectives must agree in gender.

    la libro rojo
    el libro rojo

    The article ('el'/'la') and any adjectives ('rojo'/'roja') must match the gender of the noun. Since 'libro' is masculine, you must use the masculine forms 'el' and 'rojo'.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

-o/-aFoundationsNoun Gender Markers

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Patterns that build on this one.

Words in This Pattern

-a-o