Heat is the opposite of Condition. Condition is related to Bottle. Bottle is a synonym of Nerve. Nerve is related to System. 
Dirty is related to Pollution. Pollution is related to Environmental. 
Heat <--Antonym--> Condition <--RelatedTo--> Bottle <--Synonym--> Nerve <--RelatedTo--> System 
Dirty <--RelatedTo--> Pollution <--RelatedTo--> Environmental 