underlying

From Wiktionary

Verb[change]

Plain form
underlie

Third-person singular
underlies

Past tense
underlay

Past participle
underlain

Present participle
underlying

  1. The present participle of underlie.
  2. An underlying cause, problem, or assumption, is important but hard to notice.
    You need to take care of the underlying problem before I can help.
    We're still looking for the underlying causes of the health spending increase.