Sentence:  Those indicating the student had taken a previous university French course were discarded, as were a small number of questionnaires indicating a Francophone family background (an <WSD>antirequisite</WSD> for both of these intermediate level courses) 
Meaning of the word marked with <WSD> tags:  A previous course (or learning experience) that overlaps in content with a course offering such that students may not take that course offering for academic credit.