noun-modifying (irregular)
lingual (dentistry)
Technical term in dentistry referring to the side of a tooth facing the tongue. Used attributively before nouns such as 側 (side) or 面 (surface).
Please brush the lingual surfaces of your teeth carefully.
lingual orthodontics; lingual braces
Compound of 舌 (tongue) and 側 (side), directly describing the tooth surface facing the tongue.