In very simple words, death is the end of life. So in this simple definition another term is needed to be explained and that is - life. For human being, life is the existence of an individual. If we take the term existence as an easily understood one, as because not each word can be explained in a limited opportunity, we can now define death and that is "death is the end of existence".
now mr imran Islam defines death as a mandatory transitional event in between the 'life before death' and 'life after death'. So if we integrate the scientific aspect with the description, the definition of death for a Muslim would be the absolute disappearance of the functions for the time period in between the two lives one before death and another after death. As a result it abandons the permanent and irreversible criteria of the 'end' in the concept of death with the help of the concept of the life after death.