Medical is related to Wound. Wound is related to Break. Break is a synonym of Kill. Kill is the opposite of Save. 
Fog is related to Wet. Water is a type of Wet. Tap can be used for Water. Tap is a synonym of Hit. 
Medical <--RelatedTo--> Wound <--RelatedTo--> Break <--Synonym--> Kill <--Antonym--> Save 
Fog <--RelatedTo--> Wet <--IsA-- Water <--UsedFor-- Tap <--Synonym--> Hit 