Some common reasons include: 1  a serious accident â such as a road accident, a severe head injury, a serious fall or severe burns. 2  a serious short-term condition â such as a heart attack or a stroke. 3  a serious infection â such as sepsis (blood poisoning) or severe pneumonia.
The definition of unnecessary is not needed. An example of something unnecessary is a bowl of sugar for cooking meatballs.
Garner's Modern American Usage (2009) notes that phrases like obviate the necessity or obviate the need are sometimes considered redundant, but these phrases are not redundancies, for the true sense of obviate the necessity is 'to prevent the necessity (from arising),' hence to make unnecessary..