When a woman talks about sexual fantasy she usually means an image or imagined scenario she may have in her head as she makes love.
So she may actually be in her suburban bedroom with her tubby hubby of 15 years, but in her head she is an Oriental princess in a harem being taken by her lord whose prowess is irresistible - or something like that, reports a major newspaper.
To a woman, a sexual fantasy is rarely anything she expects - or indeed would even want - to happen.
Women do quite commonly fantasise being raped. This does not, repeat not, mean that this is an experience they would in any way relish in reality. I think women find such a fantasy sexually releasing because it helps them overcome their inhibitions.
If they can kid their inner selves that they are being forced into sex, then they are able to relax into enjoying it more. And fantasy rape is not, of course, like real rape, with all the pain, terror and degradation involved.
Women know that very clearly, and usually keep their sexual fantasies to themselves. Even if their sexual dreams are quite tame, they worry that sharing it with their partner will hurt his feelings, make him feel inadequate.
Generally, women's secret sexual fantasies help them enjoy sex and are nothing to feel guilty about, no matter how lurid they are. After all, it is only a fantasy.
But if they do tell their partner, it can lead to confusion because men tend to view fantasy and to use the word quite differently. If you ask a man what is his favourite sexual fantasy he will usually tell you something he would very much like to put into practice - if he dared.
It is far less likely to be an exotic dream and more likely to be a sexual technique he particularly enjoys - especially if his partner isn't so keen on it. So a man may say his sexual fantasy is oral sex, bondage, making love to two women at once.