BibTeX: New entry for dictionary

I suggest you proceed as follows. First, change the bib entry to

@Book{DCECH,
abbreviation = {DCECH}, 
author       = {Joan Corominas and José Antonio Pascual},
title        = {Diccionario Crítico Etimológico Castellano e Hispánico ({DCECH}), 6~vol.},
year         = {1980--1991},
publisher    = {Gredos},
address      = {Madrid},
}

(Aside: Is abbreviation a field name that's recognized by the Bibliography style you employ? I don't recognize it as a standard BibTeX field.)

Second, insert the following instruction in the preamble (after loading the natbib package):

\defcitealias{DCECH}{DCECH}

Third, use \citetalias{DCECH} instead of the usual \citet{DCECH} in the body of the document generate citation call-outs that say "DCECH" rather than "Corominas/Pascual (1980-1991)".

I added the following to my .bst file :

abbreviation

as a new entry type with following code :

`FUNCTION {format.book.abbreviation}
{ abbreviation
 "abbreviation" bibinfo.check
  duplicate$ empty$ 'skip$
  {
  }
 if$
}

and below FUNCTION{book}, before author empty$, I added following code :

abbreviation empty$ 'skip$ { "" duplicate$ empty$ 'skip$ { } if$ output.nonnull.nostate format.book.abbreviation output.nonnull.nostate " = " duplicate$ empty$ 'skip$ { } if$ output.nonnull.nostate } if$ new.block

Combined with the suggestion from Mico to use \defcitealias{DCECH}{DCECH}, I new get exactly the output I need :

DCECH = Corominal, Joan/Pascual, José Antonio, Diccionario crítico etimológico castellano e histpánico, 6 vol., Madrid, Gredos, 1980-1991.

Now, the only problem left is that I have about 50 dictionaries in my bibliography and using \defcitetalias{}{} will create a very long list of definitions. Is there any way to simplify this or to create a command that will will cite the entry abbreviation instead of author.year ?