What does "people of good will" mean in Encyclicals?

Many encyclicals are directed not only to Catholics but to all "people of good will". Just a few examples: - [Laudato si](http://w2.vatican.va/content/francesco/en/encyclicals/documents/papa-francesco_20150524_enciclica-laudato-si.html) : >62. Why should this document, addressed to all people of good will, include a chapter dealing with ... - [Pacem in Terram](http://w2.vatican.va/content/john-xxiii/en/encyclicals/documents/hf_j-xxiii_enc_11041963_pacem.html) : > [...] and to the Clergy and Faithful of the entire Catholic World, and to all Men of Good Will. - [Populorum Progressio](http://w2.vatican.va/content/paul-vi/en/encyclicals/documents/hf_p-vi_enc_26031967_populorum.html) : >To the Bishops, Priests, Religious, and Faithful of the Whole Catholic World, and to All Men of Good Will. Is there an **official** understanding by the Catholic church of what people of good will mean? I searched through the [Cathecism](http://www.vatican.va/archive/ENG0015/_INDEX.HTM) , but the [two references](http://www.vatican.va/archive/ENG0015/4/GR.HTM) to good-will that exists are not related to the above. I also searched the [Catholic Encyclopedia](http://www.newadvent.org/cathen/05413a.htm) , without success.