薄弱 (bó ruò) is an adjective meaning 'weak' or 'inadequate', often describing something lacking strength, capacity, or development—especially in abstract domains like skills, systems, foundations, or physical constitution. The character 薄 (bó) originally means 'thin' or 'shallow', suggesting insufficiency or lack of depth; 弱 (ruò) means 'weak' or 'feeble'. Together, they intensify the sense of deficiency—not just physical frailty, but structural, functional, or systemic weakness.

This word is commonly used in formal or semi-formal contexts: education (e.g., a薄弱 foundation in math), healthcare (e.g., a薄弱 immune system), economics (e.g.,薄弱 infrastructure), or personal development (e.g.,薄弱 self-discipline). It carries a neutral-to-slightly-negative connotation and is rarely used for temporary or emotional states—unlike 虚 (xū) or 懦弱 (nuòruò). It typically modifies nouns directly or follows 是 (shì) in predicate position.