Science is related to Logical. Logical is a synonym of Reasonable. Reasonable is etymologically related to Reason. 
Weed is a synonym of Herb. Herb is related to Garlic. Garlic is the opposite of Onion. 
Science <--RelatedTo--> Logical <--Synonym--> Reasonable --EtymologicallyRelatedTo--> Reason 
Weed <--Synonym--> Herb <--RelatedTo--> Garlic <--Antonym--> Onion 