[1] : The Collaborative International Dictionary of English v.0.48

radicle \rad"icle\ ra^d"i^k'l, n. l. radicula, dim. of
   radix, -icis, root: cf. f. radicule. see radix. bot.
   a the rudimentary stem of a plant which supports the
       cotyledons in the seed, and from which the root is
       developed downward; the stem of the embryo; the caulicle.
   b a rootlet; a radicel.
       1913 webster
see also:
radix 

[2] : The Collaborative International Dictionary of English v.0.48

caulicle \cau"licle\, n. bot.
   a short caulis or stem, esp. the rudimentary stem seen in the
   embryo of a seed; -- otherwise called a radicle.
   1913 webster
see also:
radicle 

[3] : WordNet (r) 2.0

radicle
     n : anatomy a small structure resembling a rootlet such as a
         fibril of a nerve

Radicle >> R Words
Radicle, definition of term: Radicle
radicle_pag1.html