noun

a leader or ruler of a people or clan.

the chief of the village

leader,chieftain,head,headman,ruler,overlord,master,commander,suzerain,seigneur,liege,liege lord,potentate,sachem,leading,principal,premier,highest,foremost,supreme,grand,superior,arch-,directing,governing,number-one

adjective

most important.

the chief reason for the spending cuts

main,principal,most important,uppermost,primary,prime,first,cardinal,central,key,focal,vital,crucial,essential,pivotal,supreme,predominant,pre-eminent,paramount,overriding,leading,major,ruling,dominant,highest,arch,number-one