noun
1. : a bright green prostrate perennial Old World herb ( Astragalus glycyphyllos ) that has sulfur yellow flowers in dense spikes and is popularly supposed to increase the milk yield of goats
2. : any of various plants (as members of the genera Astragalus, Geoprumnon, and Phaca ) that are related to the common milk vetch and that include some which are highly poisonous to livestock — compare locoweed