Source : Webster's Revised Unabridged Dictionary (1913)

Thoracentesis \Tho`ra*cen*te"sis\, n. [NL., fr. Gr. ? thorax + ?
   pricking, from ? to prick, stab.] (Surg.)
   The operation of puncturing the chest wall so as to let out
   liquids contained in the cavity of the chest.