Milk thistle

Definition of milk thistle
National Cancer Institute

milk thistle

(milk THIH-sul)
A plant that has been used in some cultures to treat certain medical problems, including stomach, liver, and gallbladder disorders. The active extract of milk thistle seeds is called silymarin. It is being studied in the prevention of liver damage caused by some cancer treatments. Also called Silybum marianum.

Source: NCI Dictionary of Cancer Terms