(also 'endorrhiz) Botany ‘the sheath-enclosed radicle of an endorrhizous plant, which does not lengthen, but gives origin from its termination or from its sides to short rootlets’ ( New Sydenham Soc. Lexicon). [ < endo-prefix and comb. form + ancient Greek ῥίζα root (see rhizo-comb. form), after French endorhize, scientific Latin endorhiza (both 1808 in Richard).]