The word wheedled its way into the language of women's liberation like a semiotic sleeper agent. It was seen in headlines as early as 2007, but after the Home Office report on the sexualisation of young people last February, it was suddenly everywhere, with David Cameron wooing middle-England voters on a platform of "stopping the sexualisation of children", and Mumsnet launching their Let Girls Be Girls campaign against the "sexualisation" of children by clothes retailers.

So far this month, the Sun has blamed ra-ra skirts for 11-year-olds for sexualising girls, the Mail has pointed the finger at Madonna for allowing her daughter, Lourdes, to launch a "smouldering" fashion range which threatens to sexualise children, while elsewhere the prescription of the contraceptive pill to preteens was said to be yet more evidence of the increased sexualisation of young women. (In fact, as sexual health educators pointed out, only a tiny proportion of 11- and 12-year-olds are taking the pill, and most of them to control acne or heavy periods.)

Despite all this talk, there is little evidence that underage girls are having more sex now than they were 20 years ago: most still do not lose their virginity until the age of 16 or 17. Nonetheless, the monolithic public narrative about the sexuality of girls apparently envisions them as an army of loose-knickered slappers.

Increasingly, feminist organisations such as Object, as well as women's groups like Mumsnet have begun to use the word "sexualisation" in their campaign literature when they really mean "sexual objectification" or even "sexual abuse". This might seem like a harmless substitution, but small alterations in our language can mean a great deal.

"Sexualisation" is a troubling piece of cultural shorthand. It suggests that sexuality is something that is done to young women, rather than something that they can own and control: that they can never be sexual, only sexualised. This is not a helpful message to send to girls as they begin to explore their sexuality.

The moral panic over "sexualisation" assumes instead that sex is only ever damaging to young women, and that having sex or behaving sexually must be resisted for as long as possible. The problem is not, however, that young women are "growing up too fast" – rather it is that they are growing up to understand that they are erotic commodities, there to be used and abused, shamed if they express legitimate desires of their own, and taught to fear their own bodies.

Once, feminists fought for a woman's right to explore her erotic impulses honestly, freely and without shame. If we are to protect that legacy, today's feminists must preserve a clear distinction between the ongoing struggle to protect women and girls from abuse, and the misogynist impulse to control and police female sexuality as soon as it develops.

Ultimately, it is easier to slut-shame young women by telling them that their clothes are too sexy than to tackle cultural violence at its root. The distinction between sexuality itself and the submissive, identikit heterosexual performativity currently demanded of young women and girls is a crucial one. Only when we accept that girls have sexual agency can we ask why it is so often stripped from them by structures of violence, shame and abuse. Only when we understand that young women and girls have legitimate sexual desires can we demand to know why those desires are stolen, exploited and sold back to them by a culture that bombards them with images of perky, passive, pouting women whose defining characteristic is their erotic availability to men.