The name means "constant"/"steadfast" in Latin.
2) A guy who is horrible with girls.
3) A really hot geeky/nerdy guy. The fact that he's a geek or nerd usually contributes to the second part of the definition.
4) A complete douche bag.
2) Dylan: "So, did she ask you out?"
Kostas: "Yeah, but she broke up with me about two minutes later when she saw I liked RPG games."
Dylan: "Oh jeez, you're horrible with girls dude."
3) Kayla: "So, what are you into?"
Kostas: "Anime, video games..."
Kayla: "Whoa, major geek there!"
4) Min: "Yo, you going to the bar tonight?"
Matt: "Hell yeah!" *thinks* "Hey, maybe we should ask Kostas to join us."
Min: "That douche bag? No thanks."
From the latin word ''constant'' which means steadfast. But another meaning of constant is ''obedient, loyal'', so Kostas could mean ''loyal friend'', an awesome, good friend.
2) A name used a lot by Greeks. It's also a Christianic name.
2) Kostas is so popular in Greece, especially because it's a Christianic name, because of the GrecoRoman King Constantine, who happens to be a saint.