The only nice thing I can say about the term "cougar" is that it's a cat - and I like cats.
Honestly, at the end of the day, what does it really matter? XH was 7 months younger than I chronologically, but about as immature as they come. After he and I split, I actually dated a guy who was 7+ years younger and made XH seem like a child, maturity-wise (he turned into a good friend, we just couldn't get it going, Know what I mean?? LOL). And then there's husband - who is almost 3 years older than I am, and at times acts it, and at other times... Well, I've ranted about him.
I do not really think it matters what chronological age anyone is. I think what really matters is their level of maturity. Male, female - it depends on each person individually. And for that matter, the couple in question.