¿Cuándo hay que cambiar los adjetivos que acaban en "-c" y otra vocal por "qu" usando "ísimo"?

Sé que cuando se usa "-ísimo" con un adjetivo que acaba en "-co", la c cambia a qu y entonces se añade "-ísimo". Pero he pensado que el año pasado aprendí que hay algunos adjetivos que no cambian la c por qu, y ahora no me acuerdo de ninguno de esos adjetivos, y ninguno de mis profesores ni siquiera sabe de qué estoy hablando. ¿Alguien me puede ayudar, por favor?


I know when using "-ísimo" with an adjective that ends in "-co", the c changes to a qu and then the "-ísimo" is added. But I thought that last year, I learned that there are some adjectives that do not change the c to a qu and now, I can't remember any of the adjectives and none of my teachers even know what I'm talking about. Can somebody please help me?

  • 2
    ¡Bienvenida a Spanish.SE! I recommend you to read our FAQ, you may want to ask in Spanish so you can practise :) ¡Esperamos verte a menudo!
    – JoulSauron
    Sep 16, 2012 at 11:53

3 Answers 3


The changes you're referring to are strictly to maintain the desired sound.

Example: Rico -> Riquísimo. The only reason the change is there is because the letter C is only "hard" before A, O, and U and other consonants. Before I and E, it produces a soft sound (like S, or more accurately like Z where the two letters have different sounds). In other words, "ricísimo" does not sound the way it's supposed to, thus the letter change.

Without an example from you I can't be sure, but chances are that if you know of an adjective where the C doesn't change to QU, it's because the following vowel is an I or an E anyway, so the C already has a soft sound and thus is fine the way it is. There are no exceptions to this rule in the standard language that I'm aware of.

  • Exactly, an adjective ending in "-ce" or "-ci" would have its superlative ending in "-císimo" because of the sound.
    – JoulSauron
    Sep 16, 2012 at 11:48
  • 1
    "it produces a soft sound (like S)". Or, in some places, a soft sound like Z :)
    – dainichi
    Sep 19, 2012 at 5:11
  • Whoops! Tienes razón -- a veces se me olvidan nuestros amigos españoles.
    – Frank
    Sep 19, 2012 at 14:04

Yes, when the letter "c" is before "i" and "e" it has a soft sound so it still being "c" like for example "dulce" --> "dulcísimo"

  • 1
    ¡Buen ejemplo! Y bienvenido a Spanish.StackExchange, puedes leer sobre el sitio en nuestro FAQ, y esperamos verte a menudo por aquí (:
    – JoulSauron
    Sep 18, 2012 at 7:42

The reason for that change has nothing to do with adjectives or with the ending "-ísimo".

The writing change of your example is because of the /k/ + vowel sound that goes afterwards ("rico" is pronounced "/riko/"). The writing is different depending on the vowel following the /k/ sound. "e" and "i" are exceptions when they are following a consonant in some cases.

In my opinion (and this is how we learned it at school when we were kids) it is much better to think in sound groups that have exceptions in writing and learn them by heart, rather than thinking that "you have to change the writing to maintain the sound".

For the example you asked:

  • /k/: ca, que, qui, co, cu
  • Examples: Casa, quemar, quitar, comer, curar, are all pronounced the same (/kasa, kemar, kitar, komer, kurar/). In your case both are also pronounced the same (/riko->rikisimo/) but the orthography rule for /k/ + vowel makes the writing different: rico->riquísimo.

But this also happens with:

  • /z/: za, ce, ci, zo, zu (as it sounds in Spanish from Spain, like the "th" in "think")
  • Example: /zeniza/->ceniza
  • /g/: ga, gue, gui, go, gu -> Gato, guerra, guiño, gorro, gubia.
  • /g+u/: gua, güe, güi, guo -> Agua, desagüe, pingüino, antiguo. (Guu does not exist).

In some cases, two ways coexist, depending on the word:

  • /j/: ja, ge/je, gi/ji, jo, ju
  • Examples: Gema, jeroglífico. Girar, jirafa.

This is indeed extremely weird and confusing for children and for non-native speakers/writers. It has no logical explanation other than tradition, but that's how it is and it should be learned by heart.

Learn and practice those exceptions and you will automatize them quickly. There is no other way. This is what we did at school and believe me, it was for a reason. It's difficult, agreed, but there are not so many exceptions.

Think of the consonant+vowel sound combinations and say them aloud /ka, ke, ki, ko, ku/ while you write them down "ca, que, qui, co, cu". Say /ga, ge, gi, go, gu/ and write down "ga, gue, gui, go, gu". Etc.

You'll see how your Spanish improves really quickly.

Don't worry too much about the je/ge, ji/gi thing. Most Spanish make mistakes when writing words with /j/ + e,i sound combinations. What you really need to know though is that ge, gi always sound /je, ji/ (very important for reading aloud).

To understand to which extent this is weird and arbitrary, some oral languages that were written using Spanish orthography (e.g. Basque) recently got rid of all these exceptions/inconsistencies and simplified the writing.

Although this is quite recent (a few decades), the official and modern way of writing these consonant+vowel sound combinations in Basque is:

  • /k/: ka, ke, ki, ko, ku
  • /z/: za, ze, zi, zo, zu
  • /g/: ga, ge, gi, go, gu
  • /j/: ja, je, ji, jo, ju

As an interesting example, the traditional "Guipúzcoa" has become "Gipuzkoa" in modern Basque ortography.

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