2  definitions  found 
 
  From  Webster's  Revised  Unabridged  Dictionary  (1913)  [web1913]: 
 
  Nucleus  \Nu"cle*us\,  n.;  pl  E.  {Nucleuses},  L.  {Nuclei}.  [L.,  a 
  kernel,  dim.  fr  nux,  nucis,  nut.  Cf  {Newel}  post.] 
  1.  A  kernel;  hence  a  central  mass  or  point  about  which 
  matter  is  gathered,  or  to  which  accretion  is  made  the 
  central  or  material  portion;  --  used  both  literally  and 
  figuratively. 
 
  It  must  contain  within  itself  a  nucleus  of  truth. 
  --I.  Taylor. 
 
  2.  (Astron.)  The  body  or  the  head  of  a  comet. 
 
  3.  (Bot.) 
  a  An  incipient  ovule  of  soft  cellular  tissue. 
  b  A  whole  seed,  as  contained  within  the  seed  coats. 
 
  4.  (Biol.)  A  body,  usually  spheroidal,  in  a  cell  or  a 
  protozoan,  distinguished  from  the  surrounding  protoplasm 
  by  a  difference  in  refrangibility  and  in  behavior  towards 
  chemical  reagents.  It  is  more  or  less  protoplasmic,  and 
  consists  of  a  clear  fluid  (achromatin)  through  which 
  extends  a  network  of  fibers  (chromatin)  in  which  may  be 
  suspended  a  second  rounded  body,  the  nucleolus  (see 
  {Nucleoplasm}).  See  {Cell  division},  under  {Division}. 
 
  From  WordNet  r  1.6  [wn]: 
 
  nucleus 
  n  1:  a  part  of  the  cell  containing  DNA  and  RNA  and  responsible 
  for  growth  and  reproduction  [syn:  {cell  nucleus}] 
  2:  the  positively  charged  dense  center  of  an  atom 
  3:  a  small  group  of  indispensable  persons  or  things  "five 
  periodicals  make  up  the  core  of  their  publishing  program" 
  [syn:  {core},  {core  group}] 
  4:  (astronomy)  the  center  of  the  head  of  a  comet;  consists  of 
  small  solid  particles  of  ice  and  frozen  gas  that  vaporizes 
  on  approaching  the  sun  to  form  the  coma  and  tail 

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