ONEROUS CONCERN is a job description that describes a difficult and demanding task. It implies that the person taking on the job must be prepared to face a lot of challenges and obstacles in order to complete it. The term ONUS, which is a four-letter word, is related to this job description as it means a burden or responsibility that someone has to take on. Therefore, ONEROUS CONCERN can be interpreted as a difficult and burdensome task that requires a lot of effort and dedication to complete.