I am not sure in the least. My sister thinks that it has to be a girl, but I don't actually think it is. The reason I'm asking is because it's taken to overeating and then vomiting lately. So my sister thinks it must be pregnant - but I don't think pregnant cats actually behave like that. On top of which it doesn't appear to have nipples and also it's stomach is approximately the same size. I don't know - I'd much rather it were up the duff rather than preggers, but I really couldn't say. Also for the record - this ain't my cat, but it keeps coming to The House... and I keep feeding it... so it's kind of my cat. I don't even like cats. Seriously though, how do you tell a boy from a girl in terms of cats?
Since your cat is 'oldish' then it would be simple to find out if the cat is male or female. Most older male cats have visible scrotums so if you see that . . . well, you won't have to worry about feeding a litter of kittens.
Why not take the animal to a vet? That way you can get it checked out properly and see if it needs any kind of attention. I think somewhere you must like cats after all, otherwise you couldn't be bothered feeding it. Perhaps it came to you for a reason... saying: "adopt me permanently, please".
You referred to it as a "cat", so it must be a big one already. Have you noticed by this time that it does have a scrotum? You really can't miss it, it's easily visible. If you compare the male cat's rear part to a female cat's rear part, then you will just see a slit on the area where the scrotum is.
You pull up its skirt. Being serious though, if it was a male cat wouldn't it kind of have obvious testicles? Both of my previous cats were dudes and their stuff kind of hung in the wind when ever they walked. If you don't see anything like that then its probably a Miss.
Well to find it's gender you have to check under it's tail. Get that cat to come to you calmly then do this. If you lift up its tail and see mail genitalia (Scrotum) then it's a male cat. If you notice a lack of this part, and another hole under it's anus (usually black), then it's a female.
That is a good question lol. With dogs its easier to tell but I guess lifting the tail is what it takes to tell by checking to see if they have a scrotum or not. Come to think of it, when my cat had kittens I was able to tell which were male and female but checking under their tales.
This may not apply in your situation because it sounds like you have an older cat. However, with younger cats/kittens, I have always heard that when you look under the tail, girl kittens have a "dash". Boy kittens will have a "dot". Btw, if your cat is throwing up, it could have a hairball. Can you put some grease/butter/fat on its paw? That way, it will lick off its paw, ingest the grease and hopefully get rid of the hairball.
Go to the vet. While you are there, you can get the cat a check-up and see if it has any illnesses or parasites. This is for everyone's good, not just the cat. And if it's not fixed, please consider doing it because outdoor cats can impregnate/get pregnant easily, and nobody wants to have to deal with a litter of kittens.