https://travel.state.gov/content/tr...es/administrative-processing-information.html
What does a visa refusal under section 221(g) mean?
A visa refusal under section
221(g) of the Immigration and Nationality Act (INA) means the applicant did not establish eligibility for a visa to the satisfaction of the consular officer, as is required under U.S. law, specifically section 291 of the INA. When an applicant is refused under 221(g), it means the consular officer determined that the applicant was not eligible for a visa after completing and executing the visa application and any required interview. It is possible that a consular officer will reconsider a visa application refused under 221(g) at a later date, based on additional information or upon the resolution of administrative processing, and determine that the applicant is eligible. When a consular officer refuses a case under 221(g), she or he will convey to the applicant whether the applicant is required to provide any further documentation or information, or whether the case requires additional administrative processing.