高级 (gāo jí) is an adjective meaning 'advanced' or 'senior', formed by combining 高 (gāo, 'high') and 级 (jí, 'level' or 'grade'). Literally, it means 'high-level', and it describes something that is more complex, sophisticated, or higher in rank than standard or basic versions. It’s commonly used for courses, certifications, software, job titles, and products — for example, 高级工程师 (senior engineer) or 高级汉语课程 (advanced Chinese course).

The term carries a formal, positive connotation and often implies expertise, exclusivity, or elevated status. Unlike the standalone word 高 (gāo), which simply means 'tall' or 'high', 高级 cannot be used to describe physical height. It functions exclusively as a pre-nominal modifier — always placed directly before a noun, never predicatively (e.g., you can say 高级课程 but not *这门课很高级 in casual speech; instead use 更高级 or 非常高级 for emphasis). It’s frequently contrasted with 初级 (beginner) and 中级 (intermediate) in structured learning contexts.