The word "关键词" is formed by sequentially combining three characters: 关 (guān), which conveys a sense of relation or connection; 键 (jiàn), meaning key or pivotal element; and 词 (cí), meaning word or term. The characters 关 and 键 together create the compound 关键 (guānjiàn), meaning "key" or "crucial", which then modifies 词 (word) to specify "key word", denoting an essential term in contexts such as information retrieval or discourse.