primal

serving as an essential component; "a cardinal rule"; "the central cause of the problem"; "an example that was fundamental to the argument"; "computers are fundamental to modern industrial structure"

Source: WordNet® 3.1, Princeton University — "WordNet Copyright 2011 by Princeton University. All rights reserved." Used under WordNet's license terms. See methodology for full licensing detail. Word validity for game play may differ from any official game dictionary.