Non-Manual Sign

Facial expressions, head movements, eye gaze, mouth movements, and body posture that serve essential grammatical and linguistic functions in sign languages. In ASL, NMS perform lexical functions (distinguishing between signs like CLEAN and VERY CLEAN), morphological functions (modifying meaning, showing degree or intensity), and syntactic functions (marking sentence types such as Yes/No questions via raised eyebrows, or negation via head shake). NMS are integral to sign language grammar, not merely stylistic additions, and are particularly challenging for hearing learners to acquire.