cardinal cardinal /ˈkɑːrdɪnəl/

adjective

1. () Serving as an essential component  ( primal , cardinal , key , central , fundamental )
   serving as an essential component
    A cardinal rule
   a cardinal rule
    The central cause of the problem
   the central cause of the problem
    An example that was fundamental to the argument
   an example that was fundamental to the argument
    Computers are fundamental to modern industrial structure
   computers are fundamental to modern industrial structure
   
2. Being or denoting a numerical quantity but not order  ( cardinal )
   being or denoting a numerical quantity but not order
    Cardinal numbers
   cardinal numbers
   

noun

1. () (Roman Catholic Church) one of a group of more than 100 prominent bishops in the Sacred College who advise the Pope and elect new Popes  ( cardinal )
   (Roman Catholic Church) one of a group of more than 100 prominent bishops in the Sacred College who advise the Pope and elect new Popes
    In the Vatican, the cardinal plays a significant role in advising the Pope.
   In the Vatican, the cardinal plays a significant role in advising the Pope.
   
   
2. Crested thick-billed North American finch having bright red plumage in the male  ( cardinal , cardinal grosbeak , Cardinalis cardinalis , redbird , Richmondena Cardinalis )
   crested thick-billed North American finch having bright red plumage in the male
   
   
3. A variable color averaging a vivid red  ( cardinal , carmine )
   a variable color averaging a vivid red
   
   
4. The number of elements in a mathematical set; denotes a quantity but not the order  ( cardinal , cardinal number )
   the number of elements in a mathematical set; denotes a quantity but not the order