Definition of "underlie"

underlie

/ˌʌn.dəˈlaɪ/

verb
third-person singular simple present underlies, present participle underlying, simple past underlay, past participle underlain
1. (intransitive) To lie in a position directly beneath something.
2. (transitive) To lie under or beneath.
3. (transitive) To serve as a basis of; form the foundation of.
  Quotations
  […] she was carved into the bole of a red cedar tree. Sun and storm had bleached the wood, moss here and there softened the crudeness of the modelling; sincerity underlay every stroke.
  1941, Emily Carr, chapter 6, in Klee Wyck‎
  Some poems, echoing the purpose of early poetic treatises on scientific principles, attempt to elucidate the mathematical concepts that underlie prime numbers. Others play with primes’ cultural associations. Still others derive their structure from mathematical patterns involving primes.
  2013 July-August, Sarah Glaz, “Ode to Prime Numbers”, in American Scientist, volume 101, number 4
4. (transitive) To be subject to; be liable to answer, as a charge or challenge.
  Quotations
  The knight of Ivanhoe […] underlies the challenge of Brian der Bois Guilbert.
  1820, Walter Scott, Ivanhoe; a Romance. […], volumes (please specify |volume=I to III), Edinburgh: […] Archibald Constable and Co.; London: Hurst, Robinson, and Co. […]
5. (mining) To underlay.