twig in WordNet English dictionary

1. a small branch or division of a branch (especially a terminal division); usually applied to branches of the current or preceding year
   branchlet  twig  sprig 
   

1. understand, usually after some initial difficulty
   "She didn't know what her classmates were plotting but finally caught on"
   catch on  get wise  get onto  tumble  latch on  cotton on  twig  get it 
   
2. branch out in a twiglike manner
   "The lightning bolt twigged in several directions"
   twig