Tongue/tʌŋ/ Definition 1 of 6Pro Tip 1/2Sensory Function The tongue is key for tasting; it's sensitive to five tastes: sweet, sour, bitter, salty, and umami. She savored the sweet taste with her tongue. Pro Tip 2/2Nonverbal Expression Sticking out your tongue can be a playful gesture or a sign of rudeness, depending on the culture. He playfully stuck out his tongue at his sister.