WordNet sense 1 (the lowest tone of a harmonic series):

first harmonic, fundamental frequency

WordNet sense 2 (far-reaching and thoroughgoing in effect especially on the nature of something):

profound

WordNet sense 3 (important in effect or meaning):

important, significant

WordNet sense 4 (being or involving basic facts or principles):

rudimentary, underlying

WordNet sense 5 (pertaining to or constituting a base or basis):

basic

WordNet sense 6 (serving as an essential component):

cardinal, central, key, primal

WordNet sense 7 (of great significance or value):

of import