UD police officers searched the neighborhood but were unable to locate the suspect.
A report released by university police on Tuesday did not disclose any additional details of the incident.
No items were reported stolen and he man did not touch the student, according to the advisory.
Anyone who may have additional information regarding the incident has been asked to contact the UD Department of Public Safety dispatcher at (937) 229-2121. UD officials declined to comment further Monday on the incident.
At least three rapes have been reported to campus police since classes began on Aug. 24.
On Aug. 28, a rape was reported at an Irving Avenue location redacted in a report, according to UD police.
On Sept. 4, a rape in a Caldwell Street residence hall was reported to police, and on Sept. 12 police received a report of a separate alleged rape in Stuart Hall that also occurred on Sept. 4.
Those alleged rapes remain under investigation, according to the university.
Separately, two incidents of sexual assault that occurred in 2015 also were recently reported to police by UD Health Center physicians.
A physician reported on June 30 that a sexual assault occurred in an unknown campus residence hall between Nov. 13, 2015, and Nov. 15, 2015.
On Sept. 6, a health center physician reported that a sexual assault had occurred in a residence hall on Caldwell Street on April 22, 2015, according to police.