Neologism.

What is the antonym of fragility, its exact opposite? It does not exist. And for this reason Nassim Taleb created a neologism that completes the triad: fragile, resilient and antifragile. If “fragile” is a person (a company, a system) that does not benefit but succumbs in the face of an unforeseen and unpredictable event and that does not like chance, disorder and errors; and if resilient is the person who resists negative events, but remains true to himself because he is unable to benefit from the stress factors and uncertainty; the antifragile person takes advantage of the jolts; he takes advantage of chance and disorder, thrives and grows when exposed to volatility and stressors, and loves adventure, risk, uncertainty and the possibility of falling and failing.
If fragile organisations, subjected to an extraordinary event go under; the resilient ones withstand impact; antifragile systems change while improving.

This does not mean undermining the value of what is fragile. Fragility is not a weakness, but an intrinsic characteristic of humans and depends on the limits of the human condition and the environment in which they live. It is possible to be fragile in some situations and antifragile in others.
In fact, antifragile person embraces both fragility, which he does not deny, and resilience in a more evolved form. Having an antifragile mindset allows us to look at mistakes from a different perspective, to see falls and downturns as an opportunity to strengthen us skills and to give new impetus to our personal and professional life despite loss and defeat.

The antifragile person is not an optimist but a realist, because he is aware that a plan, even if decided down to the smallest detail, may undergo unwanted changes. He does not let himself become disheartened by the humiliation of the fall nor conditioned by the stress of success achieved after overcoming many obstacles. He considers error as inherent in the journey, not a momentary event; he knows that he does not have complete control over events but proceeds by trial and error and by taking advantage of the stumbles.