Signal is the opposite of Noise. Noise is related to Headache. Headache is a synonym of Concern. Concern is a synonym of Refer. 
Cake is related to Item. Item is related to Cross. Cross is related to Symbol. Symbol is related to Divide. 
Signal <--Antonym--> Noise <--RelatedTo--> Headache <--Synonym--> Concern <--Synonym--> Refer 
Cake <--RelatedTo--> Item <--RelatedTo--> Cross <--RelatedTo--> Symbol <--RelatedTo--> Divide 