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I see that your reading incomprehension still persists. First of all:

""In general, Wikipedia articles should rely on reliable secondary sources""

This doesnt mean tertiary sources arent reliable. And:

""General encyclopedias, like the Encyclopedia Britannica or Encarta, sometimes have authoritative signed articles written by specialists and including references. However, unsigned entries are written in batches by freelancers and must be used with caution.""

is written under the part ""Advice specific to subject area"" and ""History"". 

In other words Encyclopedic sources and hence dictionaries are reliable sources, especially when we arent discussing a historic subject such as this one. I do hope that you develop your reading comprehension. Try to read lots of books.  "