Retroflex is a term used to describe a specific type of articulation where the tip of the tongue is curled back towards the roof of the mouth. Some antonyms for retroflex include dental, labial, and palatal. Dental refers to sounds produced using the teeth, such as "th" in "then" or "thin." Labial sounds are produced using the lips, such as "p" or "b." Palatal sounds are those that involve the back of the tongue and the hard palate, such as "y" in "yes" or "sing." These are all different ways in which sounds can be articulated, creating a diverse array of language and speech patterns.