How is the plural of Spanish nouns formed?

The plural formation of Spanish nouns is quite simple. It is similar to English since the plural form also ends in ‘-s’ in most cases. The grammatical gender does not play a role. Compare in detail:

• Singular nouns that end in a vowel (a, e, i, o, u) are simply given an ‘-s’ suffix. Examples:
  • el plato → los platos (plate → plates)
  • la ventana → las ventanas (window → windows)
  • el viaje → los viajes (journey → journeys)
  • el sofá → los sofás (sofa → sofas)
    • Information: Even with stressed final vowels with an accent, only ‘-s’ is added. The accent mark is kept.
• On the other hand, the suffix ‘-es’ is appended to singular nouns ending in a consonant. The additional ‘-e-’ inside the syllable is for pronunciation:
  • el hospital → los hospitales (hospital → hospitals)
    • consonant ‘l’ at the end
  • la mujer → las mujeres (woman → women)
    • consonant ‘r’ at the end
  • la especialidad → las especialidades (specialty → specialties)
    • consonant ‘d’ at the end

What changes can occur in placing the accent mark?

When applying the rule of appending ‘-es’ to final consonants, an additional particularity in accent placement occurs with specific nouns. It is necessary to distinguish whether the last syllable is stressed or not. Then, an accent is either added or omitted in order to comply with the accentuation/stress rules.

• If a singular noun’s final syllable ends in ‘-s’ or ‘-n’ and is stressed (represented by an accent on the last vowel), this accent mark is omitted in the plural form because the rule for stressing the penultimate syllable applies. Examples:
  • el inglés → los ingleses (Englishman → Englishmen)
    • Ending in the stressed vowel ‘é + s’ in the singular; thus, the accent is dropped in the plural form.
  • la habitación → las habitaciones (room → rooms)
    • Ending in the stressed vowel ‘ó + n’. Again, the stress of the penultimate syllable must be retained, which eliminates the accent.
• In contrast, an accent is added when a singular noun’s penultimate syllable is stressed and ends in ‘-s’ or ‘-n’. Then, the word carries no accent in the singular:
  • el origen → los orígenes (origin → origins)
    • Here, the second last syllable, ‘-rig/ríg-’, is stressed, once without an accent mark and once with one.
  • la imagen → las imágenes (image → images)
    • The second last syllable is ‘-mag/mág-’ and must be accented in the plural form.
  • Be careful: This rule has exceptions. Some (few) words change the stressed syllable in the plural. Example:
    • el carácter → los caracteres (personality → personalities)
      • In the singular, the second syllable, ‘-rác-’, is stressed, but in the plural, the emphasis shifts to the third syllable, ‘-ter-’. The former accent is dropped.
  • Pay attention: Singular nouns in which other syllables, for example, the first one, are stressed with an accent mark keep it—there is no change of accent then. Example:
    • el técnico → los técnicos (technician → technicians)
    • Incorrect: los tecnicos

What other particularities can occur during plural formation?

The plural formation of nouns continues to offer two particularities in spelling, which are due to reasons of pronunciation. Details:

‘-z’ becomes ‘-ces’

• Since ‘-c’ at the end of a Spanish word is pronounced like the English ‘k’, the ‘-c’ in the singular must change to ‘-z’ to retain the sound. Furthermore, ‘-es’ is appended to form the plural. Examples:
  • la nuez → las nueces (walnut → walnuts)
    • The final ‘-z’ becomes ‘-ces’ in the plural form.
  • la raíz → las raíces (root → roots)
    • Here, the accent from the singular form is preserved in the plural form.

No additional ending in the plural

Singular and plural forms are identical for nouns ending in an unstressed vowel + ‘-s’.

• Some nouns end in ‘-as, -is’ or already in ‘-es’. In these cases, they do not get an additional plural suffix. The articles (and determiners) provide clarity about singular and plural. Examples:
  • el microondas → los microondas (microwave → microwaves)
    • ending in ‘-as’
  • el jueves → los jueves (Thursday → Thursdays)
    • ending in ‘-es’
  • la crisis → las crisis (crisis → crises)
    • ending in ‘-is’

Further explanations related to the ‘Plural formation of nouns’

The following explanations refer to the topic ‘Placing accent marks and spelling of plural nouns in Spanish’ and may therefore be interesting too:

• Consonants and vowels in the Spanish alphabet