Two horses kept in the same stable are stablemates. From that, English borrowed the word for anything that comes from the same company or the same owner. A carmaker's two models are stablemates; two magazines owned by one publisher are stablemates; two players on the same team, or two singers signed to the same record label, are stablemates. There is a useful shade of meaning inside it: stablemates are usually a bit different from each other — a cheaper model and an expensive one, a big star and a newer one — but they share a home, so what happens to one can affect the other. Writers reach for it when comparing: "The new phone is faster than its stablemate, but costs more." It belongs to business and sports journalism far more than to everyday speech; a normal conversation would just say "the other one they make". You will meet it mostly in the motoring and business pages, and in horse racing, where it kept its original sense.

同廄馬；（引申）同公司／同集團旗下的產品或人員（如同門車款、同門藝人）