sə̇ˈnēs(h)ēˌō noun
Etymology: New Latin, from Latin senecion-, senecio old man, groundsel (from its hoary pappus), from sen-, senic-, senex old, old man — more at senior
1. capitalized : a genus of very widely distributed herbs, shrubs, and trees (family Compositae) that have alternate or basal leaves and heads composed of both tubular and radiate or only tubular flowers, have the rays mostly yellow and pistillate, and have terete achenes crowned by a pappus of soft white hairs — see cineraria , groundsel I
2. -s : any plant of the genus Senecio