docs: public void add(IWord word)
      {
          //check and extends the entity from the base word
          if ( word.getEntity() == null ) {
              word.setEntity(rootWord.getEntity());
          }
          
          //check and extends the part of speech from the base word
          if ( word.getPartSpeech() == null ) {
              word.setPartSpeech(rootWord.getPartSpeech());
          }
          
          word.setSyn(this);
          synsList.add(word);
      }