I noticed that the letter "z" in Spanish is pronounced /θ/ in all circumstances, and the letter "c" is pronounced /θ/ in front of "e", "i" and /k/ in front of other vowels.

My questions are:

  1. What is the origin of these two distinct spellings? Did Latin have a more practical reason for having two different letters that represent the same sound ?

  2. Why hasn't modern Spanish reformed this redundancy, just using "z" everywhere ? Most other aspects of Spanish orthography seem to be completely coherent and phonetic.

A good example is the verbs ending with -izar, such as tranquilizar. In the first person preterite singular, it becomes tranquilicé, whereas *tranquilizé would be pronounced the same.

  • This reminded me about Los Santos Inocentes, both the book and the movie: la C con la A, hace KA, y la C con la I hace CI y la C con la E hace CE y la C con la O hace KO, y los porqueros y los pastores, y los muleros, y los gañanes y los guardas se decían entre sí desconcertados, también te tienen unas cosas, parece como que a los señoritos les gustase embromamos, pero no osaban levantar la voz, hasta que una noche, Paco (...) se encaró con el señorito alto (...) preguntó, señorito Lucas, y ¿a cuento de qué esos caprichos? (...) es la gramática, oye, el porqué pregúntaselo a los académicos
    – fedorqui
    Mar 2, 2020 at 13:53
  • @ArunabhBhattacharya I think you're mistaking /θ/ for something else. English /θ/ is never represented by anything other than th.
    – pablodf76
    Apr 28, 2020 at 12:15
  • Only few local areas in Spain pronounce these like /θ/." Most dialects pronounce these like /s/. In English also, "c" is pronounced /s/ in front of "e", "i" and /k/ in front of other vowels. In English also, there are words like "quartz" and "influenza", which pronounce the "z" like /s/."
    – Arunabh
    May 19, 2020 at 14:37

1 Answer 1


Historically they did represent different sounds, but have since merged in Spanish:

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The usual orthography in modern Spanish for /θ/ is "c" before "e, i" and "z" elsewhere.

However, some words (mostly loans) contradict this for etymological reasons, having "ze, zi" sequences. Note that many of these have 'hispanicised' variants, e.g. zinc, cinc; zebra, cebra.

  • Does it mean that tranquilicé was read "tranquilitsé" in 13-15 th century ?
    – Mintou
    Mar 1, 2020 at 15:53
  • 1
    @Mintou you picked an unfortunate example, since "tranquilizar" is a relatively new word, coined in the 18th century, but yes, that would be the then spelling to represent that pronunciation (early in that period, and similar to "tranquilisé" by the end of it). See here for more info: en.wikipedia.org/wiki/…
    – jacobo
    Mar 1, 2020 at 16:16
  • sorry for being insistent, but why would a new 18th century word not use the form "tranquilizé", what was the logic behind it ?
    – Mintou
    Mar 1, 2020 at 16:58
  • 1
    I mean, since in the 18th century there was not such distinction anymore, is it completely arbitrary that they kept this rule in from front of e and i ?
    – Mintou
    Mar 1, 2020 at 18:20

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