Adjective fundamental has 3 senses
  1. cardinal, central, fundamental, key, 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"
    Antonym: unimportant (indirect, via important)
  2. fundamental, rudimentary, underlying - being or involving basic facts or principles; "the fundamental laws of the universe"; "a fundamental incompatibility between them"; "these rudimentary truths"; "underlying principles"
    Antonyms: incidental, incident (indirect, via basic)
  3. fundamental, profound - far-reaching and thoroughgoing in effect especially on the nature of something; "the fundamental revolution in human values that has occurred"; "the book underwent fundamental changes"; "committed the fundamental error of confusing spending with extravagance"; "profound social changes"
    Antonyms: insignificant, unimportant (indirect, via significant)
,Noun fundamental has 1 sense
  1. fundamental, fundamental frequency, first harmonic - the lowest tone of a harmonic series
    --1 is a kind of harmonic