paramount

Short definition from Wiktionary

Adjective

1. 1
   Highest, supreme; also, chief, leading, pre-eminent.
2. 2
   Of the highest importance.
3. 3
   Of a law, right, etc.: having precedence over or superior to another.

Noun

1. 1
   A chief or superior; (specifically, chiefly South Africa) an African chief having the highest status in a region; a paramount chief.
2. 2
   A supreme ruler; an overlord; (specifically, historical) in the feudal system, a landowner who did not derive ownership of the land from anyone else, and who was able to grant fees to others; a lord paramount.

Proper noun

1. 1
   A city in Los Angeles County, California, United States.