Source : Webster's Revised Unabridged Dictionary (1913)

Reddle \Red"dle\ (r?d"d'l), n. [From {Red}; cf. G. r?thel. Cf.
   {Ruddle}.] (Min.)
   Red chalk. See under {Chalk}.

Source : WordNet®

reddle
     n : a red iron ore used in dyeing and marking [syn: {ruddle}, {raddle}]