Definition of pericyclic in English:
 pericyclic
adjective ˌpɛrɪˈsʌɪklɪkˌpɛrɪˈsɪklɪk
1Chemistry 
Relating to or denoting a reaction that involves a concerted rearrangement of bonding in which all the bonds broken or formed in the reaction lie on a closed ring, whether or not a cyclic molecule is involved.
 Example sentencesExamples
-  In pericyclic reactions, bonds are made or broken in a concerted cyclic transition state.
 -  But, because the mechanism for the reaction is pericyclic, there is retention of geometry such that quite specific products can be generated.
 -  Chemists everywhere are now familiar with the Woodward-Hoffmann rules for pericyclic reactions, which tied a whole list of cyclizations and rearrangements into a coherent bundle.
 
2Botany 
Relating to a pericycle.
 Example sentencesExamples
-  Azima tetracantha bark is distinctive in having bundle cap (‘pericyclic’) fibers and sclereid nests in phloem rays.