1. in the nature of something though not readily apparent

- an underlying meaning

Similar word(s): implicit, inexplicit, inherent

2. located beneath or below

Similar word(s): subjacent

3. being or involving basic facts or principles

- underlying principles

Similar word(s): basic, fundamental, rudimentary

Sentences with underlying as an adjective:

- We dug down to the underlying rock.

- Points and straight lines are underlying elements of geometry.

- Many nursery rhymes have an underlying meaning.