المعنى الاصطلاحي :

Expecting good from Allah, the Exalted, while hoping for His Mercy and Forgiveness.

الشرح المختصر :

"Husn uzh-Zhann billāh" (Having good expectations of Allah) is an obligatory part of Tawhid (Islamic monotheism); hence, Allah dispraised those who have bad expectations of Allah, and made it contradictory to Tawhid. It is an act of worship of the heart. It means that one expects that his Lord will reward him for his good deeds and accept his repentance, and that Allah will have mercy upon him and forgive him. It is a fruit of believing in the vastness of Allah’s mercy and forgiveness. "Husn azh-Zhann" (having good expectations) motivates one to do the deeds which he expects would make his supplication answered, his repentance accepted, and that he will be granted forgiveness when he asks Allah for it and will be rewarded when he does good deeds. The praised "husn azh-zhann" is that which motivates a person and urges him to do good deeds. As for reluctance to do good deeds and indulgence in sins, while having good expectations of Allah that he would be forgiven, this is indeed a delusion. "Husn azh-Zhann" also includes having trust and confidence in Allah alone without partners unto Him, and firmly believing that everything that Allah plans and decrees is good and beautiful.