高 (gāo) is a fundamental adjective meaning tall or high. It describes height (高楼, tall building; 高山, high mountain) and by extension, elevated levels in various domains (高温, high temperature; 高价, high price; 高兴, happy - literally high-spirited). For volume it means loud. As a surname 高 is common. The antonym is 低 (dī, low/short for objects - 矮 ǎi is used for people's height).