Source : Webster's Revised Unabridged Dictionary (1913)

Retroflex \Re"tro*flex\, Retroflexed \Re"tro*flexed\, a. [Pref.
   retro- + L. flectere, flexum, to bend, to turn.]
   Reflexed; bent or turned abruptly backward.

Source : WordNet®

retroflex
     v 1: bend or turn backward [syn: {replicate}]
     2: articulate (a consonant) with the tongue curled back against
        the palate; "Indian accents can be characterized by the
        fact that speakers retroflex their consonants"

retroflex
     adj 1: bent or curved backward [syn: {retroflexed}]
     2: pronounced with the tip of the tongue turned back toward the
        hard palate [syn: {cacuminal}]