Resilience is "the capacity of children to live well despite difficult circumstances in which they live".
The term is most authoritatively amplified in Rutter, M. (2006) “Implications of resilience concepts for scientific understanding” Annals of the New York Academy of Science, 1094, pp1-12:
"…Resilience is used to refer to the finding that some individuals have a relatively good psychological outcome despite suffering risk experiences that would be expected to bring about serious sequelae.
"In other words, it implies relative resistance to environmental risk experiences, or the overcoming of stress or adversity. It is not, however, just social competence or positive mental health. Both of them are important concepts but they refer to something different from resilience. Essentially resilience is an interactive concept that is concerned with the combination of serious risk experiences and a relatively positive psychological outcome despite those experiences."