noun
1. : any of several plants of the genus Mimosa with leaves sensitive to tactile stimulation ; especially : a tropical American herb ( M. pudica ) that is often cultivated in greenhouses and has palmate leaves the divisions of which are pinnate with many small leaflets and whose leafstalk droops and pinnae and leaflets close tightly when the plant is touched
2. : any of various plants (as a sensitive brier or the sensitive pea) showing motions after irritation