na·sal / ˈnāzəl/ • adj. 1. of, for, or relating to the nose: the nasal passages | a nasal spray. 2. (of a speech sound) pronounced by the voice resonating in the nose, e.g., m, n, ng. Compare with oral (sense 2). ∎ (of the voice or speech) produced or characterized by resonating in the nose as well as the mouth. • n. 1. a nasal speech sound. 2. hist. a nosepiece on a helmet. DERIVATIVES: na·sal·i·ty / nāˈzalitē/ n. na·sal·ly adv.