What is the male equivalent to the term "cougar"?
Clarifying ... The term "cougar" describes an older woman seeking younger men. So a male equivalent would be an older man seeking younger women. While we have a term for women, it seemed to me that it was historically assumed that older men sought out younger women. In other words, men who pursued women, "womanizers" "philanderers" etc. were also going after younger women so a separate term was not required. (From this site, "cougar" seems to have been first used in Western Canada around 2002.)
This is in part a sociological question. We have differentiated older women, but I suspect that the older man seeking younger women was simply part of our societal assumptions. Hollywood movies attest to this assumption.
I hope this helps ...