ENGLISH
REFERENCE

underlying

adj. · n.
US //ˌəndɝˈɫaɪɪŋ// UK //ˌʌndəlˈaɪɪŋ// un·der·ly·ing
  1. 1 basic or fundamental (adj.)
    B2 Upper Intermediate Academic

    describing the most important or basic cause of something, even if it is hidden.

    denoting a fundamental or root cause that is not immediately apparent on the surface.

    Example

    The doctor tried to find the underlying cause of her constant headaches.

    Example

    Economists argue that while the stock market crash was sudden, the underlying weaknesses in the banking system had been growing for years.

    Usage

    Usually placed before the noun it describes.
  2. 2 physically beneath (adj.)
    C1 Advanced Technical

    lying under the surface of something else.

    positioned or situated directly beneath another layer or surface.

    Example

    The gold was hidden in the underlying rock of the mountain.

    Example

    The investigation revealed that the cracks in the pavement were caused by shifts in the underlying soil during the heavy rains.

    Usage

    Often used in geological or construction contexts.
    • overlying
Show 1 more senseShow fewer
  1. 3 finance asset (n.)
    C2 Proficiency Technical Formal Law

    the real asset that a financial contract is based on.

    the primary financial instrument or asset upon which a derivative's price is based.

    Example

    If the price of the underlying goes up, the option becomes more valuable.

    Example

    The volatility of the underlying significantly impacts the premium required for these complex derivative contracts.

    Teacher's tip

    In general English, this is almost always an adjective; using it as a noun is restricted to professional financial and legal contexts.
    • underlying asset
Origin

By surface analysis, underlie + -ing.

© 2026 English Reference