There are a few different ways and contexts in which socioeconomic adversity can be expressed. First, let's define socioeconomic. This means the level in which a family lives according to their income, occupation and level of education.
Socioeconomic adversity, then, involves those living in the lower level of socioeconomic status who typically fall below the poverty level of income,have a high school education or less, and work low-paying, often minimum wage jobs.
The reason we study socioeconomics and adversity is because there is a link between the socioeconomic status of an individual and a whole range of other issues, from personal health (poor nutrition and lack of medical care impact peoples health over the long run) and safety issues to a cycle of poverty, to the likelihood that children in this adversity will also end up with low education and wages.
Socioeconomic adversity can be defined as negative effects (adversity) stemming from one's economic status relative to those around oneself and with regards to parental education and occupation (socioeconomic status). These can be measured in part by family size, owning versus renting a home and car, number of occupants per room, household size compared with parental income, parental education, and parental occupational category (job type). Many studies have been conducted on whether or not certain adverse effects stem directly from economic status.
For example, a study by Brooks-Gunn and Duncan in 1997 showed a disparity in IQ, literacy, and graduation rates among children who varied in socioeconomic status. A study by Packard et al in 2011 posited and showed evidence that the immune system in early childhood is affected by socioeconomic adversity and leads to health issues later in life, such as poor lung function, poor cognitive function, and carotid atherosclerosis. A third study by Culpin et al in 2015 discussed how depression was thought to be linked to childhood socioeconomic adversity, but that previous studies had not considered the effects of a person's LoC, or locus of control, which majorly affects how a person views his or herself and therefore strongly influences the likelihood of depression.
Socioeconomic adversity, then, includes adversity not only in circumstances, but in health and cognitive development as well.