Cathartic \Ca*thar"tic\, Catharical \Ca*thar"ic*al\, a. [Gr. ?, fr. ? to cleanse, fr. ? pure; akin to F. chaste.]

1. (Med.) Cleansing the bowels; promoting evacuations by stool; purgative.

2. Of or pertaining to the purgative principle of senna, as cathartic acid.

Source: Webster's Revised Unabridged Dictionary (1913)
 

Cathartic \Ca*thar"tic\, n. [Gr. ?.]

(Med.) A medicine that promotes alvine discharges; a purge; a purgative of moderate activity.

Note: The cathartics are more energetic and certain in action that the laxatives, which simply increase the tendency to alvine evacuation; and less powerful and irritaint that the drastic purges, which cause profuse, repeated, and watery evacuations. -- Ca*thar"tic*al*ly, adv. -- Ca*thar"tic*al*ness, n.

Source: Webster's Revised Unabridged Dictionary (1913)