the sow-thistle, in botany; a genus of the lyngenesia polygamia superflua clas. The receptacle is naked; the calyx is imbricated, and ventricose; and the pappus is plumose. There are ten species, three of them natives of Britain. viz. the oleraceus, or common sow-thistle; the arvensis, or tree sow-thistle; and the palustris, or marsh sow-thistle.

Sonchus is accounted cooling and attenuant, and accordingly prescribed in the stranguries, as also in inflammations of all kinds, to be applied externally in the form of a cataplasm.