Pepper is the opposite of Salt. Salt is related to Chemical. Chemical is related to Metal. 
Understand is a synonym of Appreciate. Appreciate is a type of Acknowledge. Acknowledge is a synonym of Recognize. Recognize is related to Face. 
Pepper <--Antonym--> Salt <--RelatedTo--> Chemical <--RelatedTo--> Metal 
Understand <--Synonym--> Appreciate --IsA--> Acknowledge <--Synonym--> Recognize <--RelatedTo--> Face 