Definitions:
any of various plants identified with greek ἄλυσσον and formerly reputed to cure hydrophobia. in early use: †any of several hoary plants of the family lamiaceae (labiatae), perhaps marrubium alysson (obsolete). in later use: any of various plants belonging to the genus alyssum, or to the genus aurinia which was formerly included in it.

a european weed, asperugo procumbens (family boraginaceae), with trailing bristly stems and small blue flowers in the leaf axils.