| en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            problematical
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            rocky
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            serious
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            serious
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            fractious
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            vexed
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            hard-fought
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            fractious
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            ticklish
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            challenging
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            herculean
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            herculean
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            problematical
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            rugged
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            nasty
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            tall
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            hard-fought
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            rocky
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            troublesome
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            thorny
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            thorny
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            tall
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            arduous
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            embarrassing
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            challenging
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            catchy
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            embarrassing
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            catchy
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            troublesome
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            trying
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            vexed
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            rugged
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            arduous
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            trying
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            nasty
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            ticklish
        
    
    
    
        (a, wn) | 
            ― SimilarTo ⟶
         
            Weight: 2.0
         | en
    
    
    
        
            difficult
        
    
    
    
        (a, wn) | Source: Open Multilingual WordNet | 
            
            
    | en
    
    
    
        
            arduous
        
    
    
    
        (a) | 
            ― SimilarTo ⟶
         
            Weight: 1.0
         | en
    
    
    
        
            difficult | Source: French Wiktionary |