cardinal

CARDINAL noun

[ C ] uk/ˈkɑːdɪnəl/ us
a priest with a high rank in the Catholic Church

кардинал
Cardinal Richelieu
cardinal adjective [ always before noun ]
 formal uk/ˈkɑːdɪnəl/ us
extremely important or serious

основной, главный
One of the cardinal rules of business is know what your customer wants.