A steakhouse is a restaurant whose main business is steak — thick pieces of beef, cooked over fire or on a hot grill. Of course it sells other food too: soup, salad, potatoes, wine, dessert. But steak is the reason people go, and it is what the restaurant is proud of. The word carries a picture with it, not just a meaning. A steakhouse usually feels a bit expensive and a bit old-fashioned in a comfortable way — dark wood, low lights, heavy plates, a waiter who asks how you want your steak cooked. It is where families go for a birthday, or where companies take clients. Americans use the word most, and the American steakhouse is where the idea comes from, but the word is understood everywhere English is spoken. It is one word, written together. You may occasionally see 'steak house' as two words, especially on older signs and in British writing, and that is not wrong — but one word is now normal. In Taiwan the picture is a little different from the American one. Our 平價牛排 shops are cheap, quick, and serve the steak on a hot iron plate with pasta and a fried egg. You can absolutely call them steakhouses, and English speakers will understand, but they may imagine somewhere far more expensive than what you meant.