Third-person singular simple present indicative form of underlie

(intransitive) To lie in a position directly beneath something. / (transitive) To lie under or beneath. / (transitive) To serve as a basis of; form the foundation of.

lying underneath / basic or fundamental / implicit

(finance) The entity from whose performance a derivative derives its value.

present participle of underlie

Misconstruction of underlay / Misconstruction of underlain

(dialectal) Poor; inferior.

(rare, obsolete) At a lower level. / (chiefly colloquial) In an inferior or inadequate manner; insufficiently (chiefly in opposition to overly).

Nonstandard spelling of underlie.

That which underlies.