Joy is related to Pleasure. you would Kiss because Pleasure. Kiss is related to Action. Action is related to Reduce. 
Fog is related to Dense. Dense is the opposite of Clear. Clear is the opposite of Smoke. 
Joy <--RelatedTo--> Pleasure <--MotivatedByGoal-- Kiss <--RelatedTo--> Action <--RelatedTo--> Reduce 
Fog <--RelatedTo--> Dense <--Antonym--> Clear <--Antonym--> Smoke 