One of the obscure yet elegant rules for acronyms in Spanish is to repeat an initial to indicate a plural noun in the acronym. Such is the case of E.E.U.U. for Estados Unidos (United States) or F.F.C.C. for Ferrocarriles (Trains) lit. ferrous ways.

I have seen this rule applied when only some of the nouns are plural an other nouns are singular, v.gr F.F.C.C.M. the acronym for Ferrocarriles de México.

However I've often seen the abbreviation for Unión de Repúblicas Socialistas Soviéticas as U.R.S.S. instead of U.R.R.S.S.S. as the rule would imply.

Note that a Single U Is used in this case since it refers to a singular union from a plurality of Soviet Socialist Republics, Soviet being a singular adjective to a plurality of Socialist Republics (Soviet Socialist republic being only one of many different kinds of Socialist Republics); hence a Single S for Soviéticas and two S for Socialistas in contrast to E.E.U.U. which refers to a plurality of States (E.E./Estados) that happen to be United (U.U./Unidos)

Is this a formal exception to the rule or is this an example of rule hierarchy for acronyms, say avoiding cacophony taking precedence over the rule of doubling a noun's initial to indicate plurals? Is this a case of simplicity and legibility being preferable to confusion caused by elegant complexity?

  • It could also be argued that the correct application of the rule should be U.R.R.S.S.S.S. doubling the initial for every plural at the cost of breaking semantic spaces, but I've never seen such use.
    – hlecuanda
    Commented May 6, 2018 at 2:41
  • I edited but then rollbacked, just to prevent the answer refer to things that are not then mentioned. But I want to note that DPD in Estados Unidos mentions: Es frecuente referirse a este país a través de su abreviatura: EE. UU. Puesto que se trata de una abreviatura, y no de una sigla, debe escribirse con puntos y con un espacio de separación entre los dos pares de letras. That is, the explanation in the question is wrong in the dots part: it is EE. UU. and not E.E.U.U..
    – fedorqui
    Commented May 7, 2018 at 12:10
  • Quite good comments on the use of dots and doubled down initials denoting plurals. I feel I should correct my question to the correct form (EE. UU. Vs E.E. U.U) however I've seen both forms in print. Adding to the confusion, coincidentally I've just heard a local radio news anchor read out loud Eh-Eh Uh-Uh instead of developing the initialism to Estados Unidos which I'm certain was a mistake, but still... It adds to the confusion around the subject of Initialisms Vs Acronyms
    – hlecuanda
    Commented May 7, 2018 at 19:26
  • 1
    The usage of Initialisms is worthy a book! In Spain there was a famous case where a TV journalist said ce ce o o instead of Comisiones Obreras to refer to a union in some news he had to broadcast. Nobody would ever call them like this, so it was quite controversial (more details in the Wiki entry I linked)
    – fedorqui
    Commented May 7, 2018 at 20:13

1 Answer 1


The actual abbreviations are EE. UU., FF. CC. M., etc. The doubling of letters is when it's just an abbreviation abbreviation — only written but never spoken (as opposed to initialisms [acronyms] like la ONU which is read as /'o.nu/ or as ONG read as letters).

In that way, the expected abbreviation for the USSR in Spanish would be U. RR. SS. SS. (note where the periods and spaces are).

These rules are, of course, not strictly followed as it's rare to find consistent use of EE. UU., although that is the correct abbreviation. Searching in Google Books, you can actually find instances of U. RR. SS. SS. being used. On the other hand, if the standard way of reading it is not to say Unión de Repúblicas Socialistas Soviéticas (thus being an abbreviation) but to read it as u erre ese ese or urs (an initialism), then the correct way to write it is URSS.

  • 1
    There's much confusion I this subject, as I've actually seen and heard people in mass media saying "La /urs/" as read direct from URSS with a soft /r/ and a slightly prolonged /s/ as to signify the double S from the URSS initialism. My search of n-gramas yielded no significant results as n-grams is notoriously poor for initialism usage, being as it may that dots do have a significant meaning in the query language. OTOH, your answer although providing a new light on the issue, leaves me with wider doubts about correct usage in this particular case :(
    – hlecuanda
    Commented May 6, 2018 at 3:29
  • If it's pronounced /urs/ then URSS would also be correct. I don't think I've heard it being said out loud, so I couldn't judge on that. Only that if it's read in full, it should be U. RR. SS. SS., and if the letters are pronounced as a word or read out, URSS. Commented May 6, 2018 at 4:07
  • @walen - Also for what I know of Latin American Spanish. (The article before "estados unidos" is optional.) Commented May 6, 2018 at 16:58
  • @walen thanks for the confirmation, I updated my answer accordingly. Commented May 7, 2018 at 0:52
  • @guifa - Please roll back if my edits don't feel right. // The trend in English is to drop lots and lots of periods in abbreviations, e.g. Mr for Mr., Mrs for Mrs., US for U.S. etc. More often in informal writing than in formal writing. I wonder if this is the case in Spanish as well. Commented May 7, 2018 at 13:44

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