/sem'peuhr vuy"veuhm/ , n.
any of various succulent plants belonging to the genus Sempervivum, of the stonecrop family, having leaves in dense basal rosettes and a compact, flat-topped cluster of flowers, and including the houseleek, S. tectorum, and other commonly cultivated species.
[ sempervivum houseleek, equiv. to L semper always + vivum, neut. sing. of vivus alive, in reference to the plant's durable qualities ]