What is the Meaning & Definition of adversity

The term adversity, traditionally, has been used to describe those situations or events which are characterized and are dominated by a significant share of calamity and misfortune. Although of course, besides to describe adverse event, also tends to be used by people to refer to those difficulties or problems that must face in their lives, i.e., all those issues that mean an extremely difficult and require patience and a significant share of virtue as the strength to overcome them.
An example to illustrate this situation which almost all human beings we face in life can be that of an individual who suddenly, after suffering an accident remains disabled persons with reduced mobility of their lower limbs. That undoubtedly is a quite adverse and unfavourable situation that will require much effort and value to be overcome.
Also, when one has e.g. planned and outlined particular personal project or professional, initiative or company, even more so, planned it up to the latest details and in which were deposited a lot of expectations and illusions, and suddenly this illusion by any internal or external contingency, disappears and is nowhere, this state of affairs can also be named and understood as an adversity.
Then, of what you mentioned, it is clear that adversity is not a situation that once it happens it is impossible to give the turn, on the contrary, however, will require major to be faced first and second after a force, courage and fortitude.