Sentence:  Few concepts are as emotionally charged as that of race. The word conjures up a mixture of associations—culture, ethnicity, genetics, subjugation, exclusion and persecution. But is the tragic history of efforts to <WSD>define</WSD> groups of people by race really a matter of the misuse of science, the abuse of a valid biological concept? 
Meaning of the word marked with <WSD> tags:  To demark sharply the outlines or limits of an area or concept.