Venn diagram
Concise Oxford English Dictionary © 2008 Oxford University Press:
Venn diagram/ˈvendʌɪəɡram/
▶noun a diagram representing mathematical or logical sets as circles, common elements of the sets being represented by intersections of the circles.
– origin early 20th cent.: named after the English logician John Venn.
'Venn diagram' also found in these Oxford entries:

