noun
    
    plural -ers
    
    [count] something (such as a fence or natural obstacle) that prevents or blocks movement from one place to another
    
    
    
    
    
    
    
    
    
    a law, rule, problem, etc., that makes something difficult or impossible
    
    
    
    
    
    
    
    something that makes it difficult for people to understand each other - often + between
    
    
    
    
    
    
    
    a level, amount, or number that is difficult to get past