Look up: Heterocyclic

1. 
   heterocyclic
   [adj] - containing a closed ring of atoms of which at least one is not a carbon atom
   Found on http://www.webdictionary.co.uk/definitio
   
   
2. 
   heterocyclic
   heterocycle; heterocyclic ring. An organic group or molecule containing rings with at least one noncarbon atom on the ring.
   Found on http://antoine.frostburg.edu/chem/senese
   
   
3. 
   heterocyclic
   organic compound containing rings or nuclei of hetero-atoms; that is to say, one or more atoms of other elements than carbon in the ring, such as nitrogen, oxygen, or sulphur. Examples are pyridine, coumarone and thiophene Category: Chemistry
   Found on http://www.mijnwoordenboek.nl/definition
   
   
4. 
   heterocyclic
   adjective containing a closed ring of atoms of which at least one is not a carbon atom
   Found on http://wordnet.princeton.edu/perl/webwn?
   
   
5. 
   heterocyclic
   (het″әr-o-sik´lik) (-si´klik) having or pertaining to a closed chain or ring formation that includes atoms of different elements.
   Found on http://www.mercksource.com/pp/us/cns/cns