Underlie v. t. : To lie under; to rest beneath; to be situated under; as, a stratum of clay underlies the surface gravel.

Underlie v. t. : To be at the basis of; to form the foundation of; to support; as, a doctrine underlying a theory.

Underlie v. t. : To be subject or amenable to.

Underlie v. i. : To lie below or under.

Underlie n. : See Underlay, n., 1.

Example:
Does the practice of polcorism Underlie much of what is decadent in present day attitudes?

Taxonomy
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Defination from the web:
underlie from the Merriam-Webster Online Dictionary with audio pronunciations, thesaurus, Word of the Day, and word games. ... to be at the basis of : form the foundation of : support <ideas underlying the revolution> 4 : to exist as a claim or security superior and ...