locoweedPronunciation: /ˈləʊkəʊwiːd/Definition of locoweed noun [mass noun] 1a plant of the pea family which can cause a brain disorder if eaten by livestock, found in the western and south-western US. Genus Astragalus (and Oxytropis), family Leguminosae 2US informal cannabis. locoweed in other Oxford dictionaries Definition of locoweed in the US English dictionary