'Taproot' definitions:

Definition of 'taproot'

From: WordNet
noun
(botany) main root of a plant growing straight downward from the stem
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"

Definition of 'Taproot'

From: GCIDE
  • Taproot \Tap"root`\, n. (Bot.) The root of a plant which penetrates the earth directly downward to a considerable depth without dividing. [1913 Webster]