After brat summer, we are now in demure autumn. Sorry, what? You see, we don’t do trends any more: we do vibes, moods that define the season. Summer’s vibe was brat; autumn’s is demure.

Funny how things work out. When the era of seasonal trends ended – no more new hemline length every September, no more new colour every spring – I think we all kind of assumed that fashion would get more sensible. That we would all, you know, find our own personal style and rotate the same three neutral-toned day-to-night outfits for ever and ever.

But that’s not quite what happened. Sure, we don’t have to stay on the new-trend-every-season hamster wheel, which is great. But as trends have started to feel less and less relevant, the idea of a “vibe” – the pop-cultural temperature – has taken hold. The trend has waned, but the vibe has waxed. Perhaps what this tells us is that there is a profound collective need to acknowledge that this crazy world is a shared experience. Or maybe that being a bit silly is part of human nature. Who knows? Anyway. The trend is dead; long live the vibe.

The brat vibe – sparked by the Charli xcx album of the same name – was about being real and a bit messy. Brat was wearing lime green, which suits absolutely no one but makes it easy for your friends to find you in a festival crowd. It was cargo pants with a cropped top. It was denim shorts with a Bic lighter in the pocket. None of that is me, if I’m honest, but I was totally here for it. As a vibe.

And when I heard that the new word of the season was demure – originating from TikToker Jools Lebron showing off her “very demure, very mindful” makeup – I felt, frankly, short-changed, less on my own account than on that of those still young enough not to get a two-day hangover from three glasses of wine. This is because, as a word, demure gives me the ick. It sounds like a warning to women to keep themselves in check. To remember that it’s not nice to be too much.

But when I noticed a £35 M&S handbag going viral for being “very demure”, I realised that by taking “demure” literally, I was getting it all wrong. Because how can a handbag be demure? This particular bag – the Faux Leather Cross Body – is very sleek, very simple, very quiet luxury. It has clean lines and plain hardware. What matters here is how demure is defined by TikTok, not how demure is defined by the OED. And the gist of demure, in the modern sense rather than the finishing-school sense, is about dialling down the chaos, practising a little self-care.

Which is how a handbag that snaps safely shut and tucks neatly under your arm is demure – because it looks low-key chic and you won’t lose your phone. Losing your phone is very brat. And annoying. At this point I realised: I could get into demure.

Demure is about 20% ironic, in that it is slightly making fun of the “clean girl” aesthetic that has buzzed around Instagram for years. Where the “clean girl” takes her skincare regime seriously, the “demure” hashtag comes with a wink to camera.

Demure is a cotton shirt tucked into an above-the-knee skirt (demure isn’t to be confused with modest dressing). Demure is a low-heeled shoe you can dance in rather than walking home carrying the spike heels that give you blisters. It is stud earrings rather than big gold hoops, a delicate necklace with a tiny dot of sparkle rather than a chunky chain. It is flossing your teeth and not getting into fights on social media, not because those are the rules but because flossing your teeth and not getting into fights on social media are good for you. It is wearing your glasses on Zoom calls rather than squinting at the text when a colleague shares their screen. It is, basically, quite sensible. But it is still – as the kids say – a vibe.

Hair and makeup: Sophie Higginson using Ouai and Lisa Eldridge beauty. Styling assistant: Sam Deaman. Model: Meja at Milk. Waistcoat, £69, and skirt, £89, both marksandspencer.com. Bag, £45, marksandspencer.com. Burgundy heels, £48, next.co.uk. Pearl necklace, £160, vbylauravann.com