underlying as in being or involving basic facts or principles
"the fundamental laws of the universe"
"a fundamental incompatibility between them"
"these rudimentary truths"
fundamentalany factor that could be considered important to the understanding of a particular business; the lowest tone of a harmonic series ; serving as an essential component; being or involving basic facts or principles; far-reaching and thoroughgoing in effect especially on the nature of something
rudimentary being or involving basic facts or principles; being in the earliest stages of development; not fully developed in mature animals