The word 土生土长 is formed by repeating the character 土 (meaning "native" or "soil") in two parallel structures: 土生, where 生 means "born", and 土长, where 长 means "grown". These components are combined into a fixed four-character idiom, creating a compound that literally denotes being born and raised in the same native place, with the repetition emphasizing completeness and local origin.