underlyingun·der·ly·ing /ˌʌndəˈlaɪ-ɪŋ◂-ər-/ adjectiveadj1underlying figure/rateECONOMICS a rate or figure that shows the real level of inflation, EARNINGS etc although it is not immediately obviousThe underlying rate of interest went up last month.
→ compare headline 2underlying security/share etcFINANCE the investment to which a DERIVATIVE such as an OPTION (=the right to buy or sell particular shares etc during a particular period of time) relatesIf the warrant is held for its full 18-month life, the value of the underlying shares would have to rise at least 18.6% to make it profitable for holders.