underlying in WordNet English dictionary

1. being or involving basic facts or principles
   "the fundamental laws of the universe"; "a fundamental incomatibility between them"; "these rudimentary truths"; "underlying principles"
   fundamental  rudimentary  underlying 
   
2. in the nature of something though not readily apparent
   "shortcomings inherent in our approach"; "an underlying meaning"
   implicit in  inherent  underlying 
   
3. located beneath or below
   underlying