ret·ro·flec·tion /ˌrɛtrəˈflɛkʃən/
反曲
retroflection
n 1: a turning or tilting backward of an organ or body part;
"retroversion of the uterus" [syn: retroversion, retroflexion]
2: an articulatory gesture made by turning the tip of the
tongue back against the roof of the mouth [syn: retroflexion]
3: the act of bending backward [syn: retroflexion]