A male, over the age of 25, who is sexually attracted to many women and has sexual interplay with many of them. He does does not seek to have a commitment to any of them. His personal moral code is that women are for sex and entertainment.
The word does not apply to males younger than 25.
The word may also apply to a lesbian.

A selfish, narcissistic, nefarious character who needs to manipulate and use woman to feed his own childish, self serving ego. Has definite “ Mommy issues.” Will often seek out girls far too young, in hopes that they'll be too naive to read his intentions. Not only will this type of predator pursue women relentlessly—using time, flattery & displaying a “sincere" interest in becoming close on an emotional/mental level—but will quickly lose interest once his true nature as a sodomizing bastard is uncovered. The fallout is ALWAYS the woman's fault, as his ego cannot handle the reality of his own fucked up behavior.

guy who makes zillions of women think he is in love with them and that he is the best guy in the universe but never know he is making 12774763836543 other women think that too

A skilled, charming man, not necessarily attractive, who can thoroughly make you believe that he loves you. Usually he is just there to get in your pants. However, there are actually some sadistic men out there who just like to do it for fun. Attention? Maybe. Revenge? Perhaps. But when you meet a charming man be very, very careful not to fall for him, he is probably an asshole.
Womanizers are the rough equivalent of female teases.

Also see Ross Ho.

a man who likes many women and has short sexual relationships with them

A man who always seems to make women fall for him.

a stupid song made in 2008. More than half the people who listen to it do not even know what "womanizer" means or can spell it.

A guy that makes a girl fall for him, yet she doesn't know he's doing the same thing with 23904394839483298432984 other girls.