underlying

American  

[uhn-der-lahy-ing] / ˈʌn dərˌlaɪ ɪŋ /

adjective

1. lying or situated beneath, as a substratum.

2. fundamental; basic.

   the underlying cause of their discontent.

3. implicit; discoverable only by close scrutiny or analysis.

   an underlying seriousness in his witticisms.

4. (of a claim, mortgage, etc.) taking precedence; anterior; prior.

5. Linguistics. belonging to an earlier stage in the transformational derivation of a sentence or other structure; belonging to the deep structure.

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underlying British  

/ ˌʌndəˈlaɪɪŋ /

adjective

1. concealed but detectable

   underlying guilt

2. fundamental; basic

3. lying under

4. finance (of a claim, liability, etc) taking precedence; prior

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Usage

What does underlying mean? Underlying most literally means situated underneath—lying under something, as in We have to fix the underlying layer before repairing the surface.Underlying perhaps most commonly means fundamental or basic. This sense of the word is used to describe things that are the basis, foundation, or cause of something else. A person’s underlying beliefs are their most essential beliefs, the ones that all their other beliefs, opinions, or values are based on. A single, underlying issue may be the basis of many other problems. Symptoms are caused by an underlying condition or disease.Less commonly, underlying can be used to describe something that lies beneath in a figurative way, especially something that’s difficult to detect because it’s partially hidden, such as underlying guilt or the underlying theme of a poem.Underlying is also the continuous tense (ing- form) of the verb underlie, meaning to literally lie beneath or to be the basis or foundation of, as in This is the main problem that underlies all the other issues. In a financial context, underlying is used more narrowly as a way of indicating what came first or what has precedence, such as in things like mortgages or insurance claims.Example: We are still working to determine the underlying cause of the collapse.

Etymology

Origin of underlying

First recorded in 1605–15; underlie + -ing ²

Example Sentences

The 22 clubs who have submitted their books for 2024-25 have lost a combined £317m, if you take into account Stoke's underlying numbers without the £90m written off loan.

From BBC • Apr. 5, 2026

It points scientists toward the underlying cognitive and communicative forces that shape human language.

From Science Daily • Apr. 5, 2026

AI startups such as OpenAI and Anthropic could be better positioned to successfully implement FDEs, Luria added, due to these companies’ ability to hire top talent, along with their strong underlying software and engaged customers.

From MarketWatch • Apr. 4, 2026

Even so, “when he and Russell reran their data set of opinion articles through the current version, the underlying assessments were similar to those in the earlier iteration.”

From The Wall Street Journal • Apr. 3, 2026

He was a member of the Eleatic school of thought, whose founder, Parmenides, held that the underlying nature of the universe was changeless and immobile.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife

Related Words

• basic
• elemental
• hidden