Futanari is the full term for futa. And its a kind of hentai where a female has both a vagina and a dick. You guys are right futa means 2 in this case. The nari part is like "to become" so i think its supposed to be interpreted as "became two" as usually in the story the girl grows a penis somehow while keeping vagina
So im not a futanari bc i dont have a vagina. But I see lots of ppl online besides phillies using it to refer to m2f, chicks w/dicks, sluts w/nuts, Annas w/bananas, Denises w/penises, girls w/o vaginas, guys-who-talk-too-much, etc.