Who exactly can be called a hafidh?

In popular parlance hafidh or hafiz seems primarily to refer to a person who has memorized the whole Qur'an. But when we read books we find this title mostly used to introduce a hadith scholar such as al-Hafidh ibn Hajar , al-Hafidh al-'Iraqi , al-Hafidh a-Dhahabi , al-Hafidh ibn 'Abd al-Bar , al-Hafidh ibn Kathir , al-Hafidh al-Bazzar etc. (if we don't call them Imams) so they are referred to as muhaddith and (imam) hafidh محدث وإمام حافظ. Of course based on the typical religious education of Muslim scholars all of these people have certainly memorized the Qur'an, so my question is who exactly is a hafidh, and what topic(s) must his knowledge cover or who is eligible to be called hafidh? **Note** in Morocco usually a person who had memorized the Qur'an is called talib (Student) as he just reached the very first step in a possible scholarly career.