underlying as in in the nature of something though not readily apparent

• "shortcomings inherent in our approach"
• "an underlying meaning"

Synonyms

• implicit in(p)
• inherentexisting as an essential constituent or characteristic; in the nature of something though not readily apparent

underlying as in located beneath or below

underlying as in being or involving basic facts or principles

• "the fundamental laws of the universe"
• "a fundamental incompatibility between them"
• "these rudimentary truths"
• "underlying principles"

Synonyms

• 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
• rudimentarybeing or involving basic facts or principles; being in the earliest stages of development; not fully developed in mature animals