I just finished reading a book recommended by some on here called "Every Woman's Guide to Cycling" by Selene Yeager. She defines a hybrid in a nutshell as "A little bit road, a little bit off-road. Does neither spectacularly but both reasonably well." She goes on to classify the following as "Hybrid": flat-bar road bikes, cyclocross bikes. She discusses "special features" as including "medium-size tires that let your roll briskly yet provide stability on moderately bumpy terrain like rough roads and cinde paths. The head-up, traffic-friendly position provides added comfort and lets you peer easily down the road, making hybrids good commuting and all around exercise bikes".
Anyway, some people are just insecure in themselves and want to make you feel that way too. Good thing you just ignored their snide remark.