Expression is a synonym of Term. Term is related to Bill. Bill is the opposite of Straight. Straight is related to Bat. 
you are likely to find Lighting in/at/on Theater. Lighting is related to Lamp. Lamp is related to Post. 
Expression <--Synonym--> Term <--RelatedTo--> Bill <--Antonym--> Straight <--RelatedTo--> Bat 
Theater <--AtLocation-- Lighting <--RelatedTo--> Lamp <--RelatedTo--> Post 