修筑 is a compound verb meaning 'to build' or 'to construct', especially large-scale infrastructure such as roads, railways, dams, canals, or fortifications. The first character 修 (xiū) originally meant 'to repair' or 'to improve', carrying a sense of refinement or restoration; the second character 筑 (zhù) means 'to build' or 'to erect', often with connotations of solid, foundational construction — historically linked to rammed-earth building techniques. Together, 修筑 emphasizes purposeful, substantial, and often labor-intensive construction projects, typically undertaken by governments, engineering teams, or large workforces.

This word is formal and commonly found in news reports, official documents, historical accounts, and technical descriptions. It is rarely used for small-scale or domestic building (e.g., constructing a house), where terms like 建造 (jiànzào) or 盖 (gài) are more appropriate. 修筑 frequently appears in passive or agentless constructions (e.g., ‘这条铁路正在修筑中’) and pairs with nouns denoting infrastructure: 道路、桥梁、堤坝、城墙、隧道.