lying or situated beneath, as a substratum.

fundamental; basic

the underlying cause of their discontent.

implicit; discoverable only by close scrutiny or analysis

an underlying seriousness in his witticisms.

(of a claim, mortgage, etc.) taking precedence; anterior; prior.

Linguistics . belonging to an earlier stage in the transformational derivation of a sentence or other structure; belonging to the deep structure.

adjective

secondary

adjective

basal , basic , bottom , bottom-line , cardinal , concealed , critical , crucial , elemental , elementary , essential , hidden , indispensable , intrinsic , lurking , necessary , needful , nitty-gritty * , nub , primary , prime , primitive , radical , root , substratal , veiled , vital , foundational , fundamental , original , ultimate , beneath , implicit , innate , latent , subjacent , substantive , substrative , underneath