In British English, cornflour is a fine white powder made from maize. Cooks mix a little with cold water, then stir it into soup or sauce so the liquid becomes thicker and shiny. It has almost no taste of its own. In American English the same kitchen powder is called cornstarch, not cornflour. Though actually, if an American says “corn flour” as two words, they may mean maize ground for baking — closer to cornmeal — not the thickener. So the British cooking word and the American baking phrase look alike but are not always the same thing. Though actually again: in older British English, corn often meant wheat or grain in general, but the white tin in the kitchen is from maize. In a Taiwanese kitchen, British cornflour matches 玉米澱粉. 太白粉 thickens in a similar way, but it is usually potato starch, not this.

玉米澱粉（英式名稱；美式叫 cornstarch。太白粉多半是馬鈴薯澱粉，不是這個。）