Every industry has their own way of talking. In the food world, a “four top” is simply a table for four people, while in corporate America, the phrase “let’s take this offline,” really just means let’s have a side conversation about this later. Fashion is exactly the same way. Though certain words and sayings come and go, like the use of “fierce” for example, the fashion singular is one that everyone loves to use. Example: “A good pant is key to your wardrobe,” or “That boot is ideal for an evening out.” Fashion writer Hadley Freeman describes it perfectly.
“American fashion stylists … all talk like Californian teenagers … they started using the fashion singular on notes given out at fashion shows … fashion journalists noticed this and perceived it as a form of Botox for the voice as it freezes one into a permanently teenage state … it started appearing in fashion magazines … lo, the fashion singular.”
Now add the use of the fashion singular to your lexicon and annoy grammar teachers all over. [Guardian]