First and Underlying

First adjective - Coming before all others in time or order.

Underlying and first are semantically related in fundamental topic. In some cases you can use "Underlying" instead an adjective "First".

Nearby Word: firstly

Underlying adjective - Of or relating to the simplest facts or theories of a subject.

First and underlying are semantically related in fundamental topic. Sometimes you can use "First" instead an adjective "Underlying".