GQ is a monthly magazine for men, published in the UK and the US and under the same name in other countries. The letters first stood for Gentlemen’s Quarterly, and the magazine is known for men’s clothes, watches, grooming, and long articles about well-known men, health, and how to live in a polished way. The tone is glossy and fashionable, not academic. People use GQ as a proper name, the way they say Vogue: you read GQ, you appear in GQ, a watch is “in GQ this month.” In Taiwan there is a Chinese-language GQ as well, so many readers just say the two letters. Though actually, you may also hear “he looks very GQ” in informal English, meaning dressed like a magazine page; that stretch is playful and a bit dated, and it is not the meaning the dictionary is filing here. The core use is still the magazine’s name.