fundamental
    /ˌfʌndəˈmɛntn̩/ 
    
 
    
    adjective
    
    [more ~; most ~]
    
    forming or relating to the most important part of something :basic
    
    
    
    
    
    
    
    
    
    of or relating to the basic structure or function of something
    
    
    
    
    
    
    
    
    
    noun
    
    plural -tals
    
    [count] :one of the basic and important parts of something :a fundamental part - usually plural