a tree or shrub that hasany of a genus of tropical and subtropical trees, shrubs, and non-woody plants of the pea family that have globular heads of small yellow flowers and leaves that droop or close in response to light, touch, etc: genus Mimosa
an acacia tree with sweetly scented yellow flowers in compact globular clusters: Acacia dealbata
[from the Latin genus name, from mimus mime; from its apparent imitation of animal sensitivity when touched]