It's usually translated as meaning a male pervert, prostitute or child molester. The sex of the victim or reciever is unimportant.
I think it's important to note that the word is not found in the diologues of Plato (or any pre-scripture Greek authors) who certainly would have used a word meaning "homosexual" if it was in his lexicon.
I'm leery of drawing any conclusion about the meaning of
arsenokoitai in the NT based on the absence of such word in the Plato. For one thing, the classical Greek of the Platonic dialogues and the Koine of the NT are separated by four centuries. Compare, for example, the english of four centuries ago as found in the King James Version with the english of the NIV -- it should come as no surprise to anyone that the word
arsenokoitai is not translated as
homosexual in the KJV but
is translated as
homosexual in the NIV when one considers that the english word
homosexual wasn't even coined until a little over a century ago!
Another point worth noting is that there is evidence that some of the NT koine is itself a translation of another language. For example, there's ample evidence to suggest that the koine found in the gospel of Matthew is a translation of an earlier semitic text. (This, too, should come as no surprise when one considers the hellenization of semitic names, such as Petros for Kephas.)