underlying

adjective

1. lying or situated beneath, as a substratum.
2. fundamental; basic: the underlying cause of their discontent.
3. implicit; discoverable only by close scrutiny or analysis: an underlying seriousness in his witticisms.
4. (of a claim, mortgage, etc.) taking precedence; anterior; prior.
5. Linguistics. belonging to an earlier stage in the transformational derivation of a sentence or other structure; belonging to the deep structure.

verb (used with object), un·der·lay, un·der·lain, un·der·ly·ing.

1. to lie under or beneath; be situated under.
2. to be at the basis of; form the foundation of.
3. Grammar. to function as the root morpheme or original or basic form of (a derived form): The form “boy” underlies “boyish.”
4. Finance. to be primary to another right or security.

adjective

1. concealed but detectableunderlying guilt
2. fundamental; basic
3. lying under
4. finance (of a claim, liability, etc) taking precedence; prior

verb -lies, -lying, -lay or -lain (tr)

1. to lie or be placed under or beneath
2. to be the foundation, cause, or basis ofcareful planning underlies all our decisions
3. finance to take priority over (another claim, liability, mortgage, etc)a first mortgage underlies a second
4. to be the root or stem from which (a word) is derived“happy” underlies “happiest”

v.Old English under licgan “to be subordinate to, to submit to;” see under + lie (v.2). Meaning “to lie under or beneath” is attested from c.1600; figurative sense of “to be the basis of” is attested from 1852 (implied in underlying).