basically what ever other definiton says but in this case the female in question is a fucking godess sexy angel its used to complitment the female and an insult to the males only.
''Man that clan is such a simp clan''
''Did you see those snapchats?? What a fucking simp XD''
''Yeah it sucks how they simp for my gf what a bunch of losers''
A man who obsesses over women, giving them all your time, money, dignity, and justifying red flags all while playing it off as "being a nice guy" is being a simp.
Keep in mind, being a simp/simping isn't defined by "being nice to women". Being nice to women is normal.
Correct use of the word:
Guy 1: "My girlfriend just took $300 from my bank account to go shopping without my permission."
Guy 2: "You gonna break up with her?"
Guy 1: "No, she probably didn't mean it."
Guy 2: "You're such a simp."