Contribution is a synonym of Share. Share is a synonym of Divide. 
Occasional is a different concept from Common. Common is the opposite of Holy. Holy is etymologically related to Whole. 
Contribution <--Synonym--> Share <--Synonym--> Divide 
Occasional <--DistinctFrom--> Common <--Antonym--> Holy --EtymologicallyRelatedTo--> Whole 