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Webster 1913 Edition
Cothurn
Co′thurn
(k?′th?rn)
, Noun.
 [L. 
cothurnus
, Gr. [GREEK][GREEK][GREEK][GREEK]. Cf. Cothurnus
.] A buskin anciently used by tragic actors on the stage; hence, tragedy in general. 
The moment had arrived when it was thought that the mask and the 
cothurn 
might be assumed with effect. Motley.