The word "发牢骚" is formed by combining the character 发, meaning "to issue" or "to express", with 牢骚, a noun meaning "complaints" or "grievances". 牢 originally denotes "prison" or "confinement", implying pent-up discontent, while 骚 means "disturbance" or "unrest", together capturing the idea of grumbling; thus, the compound literally signifies "to express complaints".