rad·i·cle 
(rădĭ-kəl)
(rădĭ-kəl)n.
1. Botany The part of a plant embryo that develops into a root.
2. Anatomy A small structure, such as a fibril of a nerve, that resembles a root.
[Latin rādīcula, diminutive of rādīx, rādīc-, root; see wrād- in the Appendix of Indo-European roots.]