D defs.my
Entry 3 senses Webster, 1913

underlying

/ŭnˌ-dẽrl-ī'-ĭng/ · un·der·ly·ing · IPA /ˌʌndərlˈaɪɪŋ/
01 a. Lying under or beneath; as, the underlying strata of a locality.
  1. 1.
    Lying under or beneath; as, the underlying strata of a locality.
  2. 2.
    Fundamental; basic; as, underlying principles; underlying causes.
  3. 3.
    Implicit; not immediately obvious; requiring careful scrutiny to discover; as, the underlying sarcasm in her seemingly innocuous remark..