A friend of mine - a woman in her 60s - recently met with a beauty therapist who performs a technique known as 'microblading'.
For the uninitiated, it's a semi-permanent eyebrow filling treatment that gives the appearance of fuller brows, and it's popular with women who, like my friend, have just come through a cycle of chemotherapy.
The beauty therapist examined her face and eventually suggested that she go for what she called 'The Cara'.
When my friend told her that she didn't know who, or what exactly, a 'Cara' was, she was informed that the style was inspired by model Cara Delevingne who, at 24 years of age, is a good 40 years younger than her. "She's an 'It Girl'," added the beauty therapist, as if it made a difference.
In an era where the uprising of women is inescapable, isn't it strange that the use of the word 'girl' to describe grown women has become so widespread?
It girl. Golden girl. Weather girl. Some people talk about "getting a girl" when hiring an au pair.
Others refer to the woman who works on the front desk of a business as "the girl on reception".
Incidentally, the beauty therapist that my friend consulted with assured her that one of her "best girls" would do the job.
Within popular culture, the girl word is often used to describe female protagonists who are in fact fully-fledged women. The Gilmore Girls; 2 Broke Girls; The Girl With the Dragon Tattoo; The Girl on the Train; Gone Girl.
More recently, the makers of TV show Supergirl came under fire for not calling the 24-year-old superhero at its helm Superwoman.
Elsewhere, we have Sophie Amoruso's #GirlBoss movement, which sounds more like an 80s family comedy starring Tom Hanks, and Beyoncé jumping aboard the socially conscious bandwagon by asking, 'Who runs the world?' (Girls, apparently.)
And let's not forget the Spice Girls' brand of Girl Power (complete with a pigtailed Baby Spice sucking on a lollipop) or the missed opportunity that was the Riot Grrrl movement (surely Riot Woman would have been more empowering and thus enduring?).
The rampant branding of the g-word suggests that marketeers purposely veer away from the word 'woman'. Girl conveys fun and frivolity. 'Woman' means business. 'Girl' sells. 'Woman' has a sell-by date.
We're beginning to understand that the language we use can reinforce systemic inequality, but just as we consider the subtle sexism of words like mankind, sportsmanship and forefathers, we ought to give more thought to the use of the word 'girl' when describing women.
Girl suggests juvenility and vulnerability at worst, arrested development at best. Crucially, it infantilises and undermines women by suggesting that they have a long way to go before they reach womanhood.
And that's if womanhood is a stage they even wish to reach. Let's be honest, many women avoid using the word 'woman' because it is synonymous with ageing. While the words 'man' and 'manhood' have inherent gravitas, the words 'woman' and 'womanhood' suggest that it's time to start shopping in Marks & Spencer.
The trickle-down effect is obvious. When we unconsciously believe that girlhood is the most desirable phase of life, we become complicit in the great charade.
Comedian Katherine Ryan puts it best: "If you have to - if you insist on - growing beyond the age of 18, you can get away with it if you look and act like a baby."
Sure enough, women who think of themselves as girls - or worse, 'girlie girls' - are generally the same women who have adopted an affectation known as 'sexy baby voice'. Actress and writer Lake Bell, who wrote a film about the phenomenon, describes it as a combination of high-pitched upspeak and vocal fry. In other words, it's the voice your annoying housemate adopts when she's hungover and asking her boyfriend to order her a pizza.
This extended girlhood is part and parcel of our youth-obsessed culture where Willow Smith is a fashion icon; the fictional schoolgirl Hermione Granger (and her real-life counterpart Emma Watson) is a feminist icon and a 60-odd-year-old woman is told that she should try to look more like Cara Delevigne.
On International Women's Day, it's worth remembering that women wouldn't have made giant strides in the workplace if we were still using the terms 'working girl' and 'Girl Friday'.
It's also worth asking where else the word is holding us back. International Girls' Day doesn't have quite the same ring to it, after all.