Root is part of Nail. Root is a synonym of Settle. Settle is the opposite of Wander. 
Wall is a type of Difficulty. Difficulty is related to Danger. Danger is related to Concept. Abstract is a type of Concept. 
Nail <--PartOf-- Root <--Synonym--> Settle <--Antonym--> Wander 
Wall --IsA--> Difficulty <--RelatedTo--> Danger <--RelatedTo--> Concept <--IsA-- Abstract 