Are there any rules for forming the plurals of loanwords?

I ask, as I was recently reminded of a sign I saw in an Office Depot in Mexico advertising "mouses".

Can this be correct in Spanish, or is it proper form to use the English plural "mice" in this case? If "mouses" is proper in this case, are there other examples where the plural form is also borrowed from an original language, but the Spanish plural would be considered incorrect?

NOTE: I know we're guilty of the same class of error in English, when we talk about a single tamale.

  • I don't understand this part of your question: "but the Spanish plural would be considered incorrect" -- I'm getting confused about the point of view when you say "considered incorrect." May 8, 2018 at 14:04
  • 1
    @aparente001: Example: Suppose Spanish accepted "mice" as the plural of "mouse", would "mouses" then be considered incorrect, or would both versions be considered correct?
    – Flimzy
    May 9, 2018 at 8:20

2 Answers 2


There are rules for extranjerismos:

  • Palabras terminadas en -l,-r,-n,-d,-z,-j. Forman el plural en -es: píxeles, másteres, pines, raides, interfaces, sijes. Se exceptúan las palabras esdrújulas, que permanecen invariables en plural: los trávelin, los cáterin.
  • Palabras terminadas en -s,-x,-ch. Algunas se mantienen invariables (campus, sioux); otras hacen el plural en -es (valses, faxes, sándwiches).
  • Palabras terminadas en consonantes distintas de -l,-r,-n,-d,-z,-j,-s,-x,-ch. Hacen el plural en -s: esnobs, chips, cómics. Se exceptúa el término imam, cuya forma plural es imames. La palabra club tiene dos plurales: clubs y clubes.
  • Palabras terminadas en dos o más consonantes. Hacen el plural en -s: gongs, icebergs, récords. Se exceptúan las palabras test, trust y kibutz, que permanecen invariables en plural, y los términos lord y milord, cuyos plurales son lores y milores, respectivamente. También se excluyen las palabras acabadas en consonante + s, que hacen el plural en -es (valses) permanecen invariables (fórceps).

Your word "mouse" is not a major problem as it ends in vowel, so it would apply the normal rule to add an -s.

  • Great answer. A couple things I didn't understand: raides, sije, trávelin, cáterin. (I looked at the source but you faithfully copied it without introducing any typos, so that didn't help me.) May 8, 2018 at 14:08
  • @aparente001 Add -es: el raid > los raides, el sij > los sijes (this is a typo on the page). Invariant: el trávelin > los trávelin; el cáterin > los cáterin
    – jacobo
    May 9, 2018 at 9:43
  • @ukemi - My problem is I don't understand those four words and haven't been able to find them. Are these terms all from the IT world? May 9, 2018 at 17:34
  • @aparente001 They all (excepting cáterin) have entries in the RAE: sij = Sikh; raid = [military] raid; trávelin = travelling/tracking shot; cáterin = catering
    – jacobo
    May 9, 2018 at 17:57

This is an anglicism. I cannot speak of all Spanish speaking countries but in Mexico it is very common that people use the English word for some computer terms, in this case "mouse" and instead of using the Spanish word "ratón".

The problem is that a lot of people think that that is the actual name of the device and they pluralize it as if it were a Spanish word which, of course, is not correct, but it has now become the common way of calling it.

  • Yes, he knows it's a loan word, and he is asking about how to deal with them.
    – JoulSauron
    May 9, 2012 at 14:51
  • Isn't it the actual name of the device, though? I don't understand. Also, when you say "not correct," for which language is it not correct? I'm confused about your point of view. May 8, 2018 at 14:06
  • @aparente001 I agree with you this is confusing and does not answer the question but he makes a good point That is NOT the actual name of the device. Mouse is the name of the device in English. In Spanish the device is called ratón so just the fact of using mouse is wrong and make it plural, more so... well at least if we are talking about Spanish and not about office depot marketing
    – DGaleano
    May 9, 2018 at 14:11

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