Al-Mudhnibin or Mudhnibon is a plural of Mudhnib المُذْنِبُ which is the person who committed a sin ذَنْبٌ see for example in the quran (40:3, 81:9 ...). So the meaning would be "Oh intercessor of the sinners". Due to the meaning شَفِيعٌ Shafi'a can't be a name of Allah, but could be used to reference the Messenger of ... More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.