oversight
n. C / Un. a mistake made because you did not notice something or forgot to do it. It can also mean the job of watching over a project to make sure it is done correctly.
n. an unintentional failure to notice or do something; alternatively, the state or act of supervising a process or organization.
Leaving your name off the form was a simple oversight.
The committee provides independent oversight of the project to ensure all safety regulations are followed.
While the error was initially dismissed as a minor oversight, subsequent investigations revealed a systemic lack of administrative control within the department.
From over- + sight. Verb sense 2 is a semantic loan from German Aufsicht.
In the sense of a mistake, it is typically countable; in the sense of supervision, it is often uncountable.