Taproot
['tæpruːt]
Definition
(noun.) something that provides an important central source for growth or development; 'the taproot of his resentment'; 'genius and insanity spring from the same taproot'.
(noun.) (botany) main root of a plant growing straight downward from the stem.
Inputed by Chris--From WordNet
Definition
(n.) The root of a plant which penetrates the earth directly downward to a considerable depth without dividing.
Edited by Glenn