underlying (root: underlie)

• POS: Adjective
• HYPHEN: un=der=ly=ing

CIDE DICTIONARY

underlying, a. 

•  Lying under or beneath; as, the underlying strata of a locality.  [1913 Webster]
•  Fundamental; basic; as, underlying principles; underlying causes.  [1913 Webster]
•  Implicit; not immediately obvious; requiring careful scrutiny to discover; as, the underlying sarcasm in her seemingly innocuous remark..  [PJC]

OXFORD DICTIONARY

underlying, pres. part. of UNDERLIE.

THESAURUS

underlying

ab ovo, basal, basic, basilar, between the lines, bottom, cardinal, constituent, constitutive, covert, critical, crucial, cryptic, delitescent, dormant, elemental, elementary, esoteric, essential, foundational, fundamental, gut, hibernating, hidden, indispensable, latent, lurking, material, muffled, mystic, necessary, needful, obfuscated, obscured, occult, of the essence, original, possible, potential, primal, primary, primitive, radical, rudimentary, sleeping, submerged, substantial, substantive, under the surface, unmanifested, veiled, virtual, vital