The word 愁眉苦脸 is formed by combining two descriptive phrases: 愁眉, meaning 'worried eyebrows,' and 苦脸, meaning 'bitter face.' Each character contributes directly to the overall meaning: 愁 (worry) modifies 眉 (eyebrows), and 苦 (bitter) modifies 脸 (face). Together, they depict a facial expression of distress, where the eyebrows show sorrow and the face shows suffering, creating a compound term for looking unhappy.