Green’s Dictionary of Slang

fessor n.

[abbr.]
(US black)

a professor, i.e. male teacher.

[US]DN III 310: Fesser. . . Professor. . . Every man that teaches is called a professor.
[US] ‘Handed-down Campus Expressions’ AS VI:2 129: ‘Fessor’ is in common use, even by the townsfolk. ‘’Fess’ is less commonly, yet frequently heard.
[US] in DARE.
[US]A. Garber Mountain-ese 29: The fessor called Johnny inter his office fer throwin’ spitballs [HDAS].
at www.unt.edu [Internet] Thomas P. Sovik, associate professor of music, won the 2002 ’Fessor Graham Award, the highest honor bestowed by the student body at UNT. [...] It is named for the late Professor Floyd Graham.