English Reference

Word

lambda

Phoneticslamb·da

US/ˈɫæmdə/

UK/lˈæmbdɐ/

Definitions

01Greek letter

B2

n. the eleventh letter of the Greek alphabet.

n. the eleventh letter of the Greek alphabet, represented as Λ (uppercase) or λ (lowercase).

“The professor wrote the Greek letter lambda on the blackboard.”

“The student struggled to distinguish between the handwritten lambda and other similar characters in the ancient manuscript.”

02wavelength

C1 · Physics

n. a symbol used in physics to represent the length of a wave.

n. the standard symbol (λ) used in physics to denote wavelength, particularly in optics and acoustics.

“In this equation, lambda represents the wavelength of the light.”

“The experiment required precise measurement of the lambda value to determine the refractive index of the new composite material.”

Technical

Synonyms

03programming function

C1 · Computing

n. a small, simple function in computer code that does not have a name.

n. an anonymous function in computer programming, often used for short-lived operations or as arguments to higher-order functions.

“You can use a lambda to sort the list without writing a full function.”

“The developer refactored the code by replacing the named helper function with a concise lambda expression to improve readability.”

Technical

04cosmological constant

C2 · Science

n. a symbol for the energy density of space in the universe.

n. the symbol (Λ) for the cosmological constant in Einstein's field equations of general relativity.

“Scientists use lambda to talk about how the universe is expanding.”

“The precise value of lambda remains one of the most significant questions in modern physical cosmology.”

Technical

Synonyms

cosmological constant

05finance/options

C2 · Finance

n. a measure of how much an option's price changes compared to the asset it is based on.

n. a measure of leverage in options trading, representing the percentage change in option value relative to a percentage change in the underlying price.

“The trader checked the lambda to see how risky the investment was.”

“High lambda values indicate significant leverage, which can amplify both gains and losses in a volatile market environment.”

Technical

Synonyms

06anatomy/skull

C2 · Medicine

n. the point on the back of the skull where two bone lines meet.

n. the craniometric point at the junction of the sagittal and lambdoid sutures.

“The doctor examined the lambda on the patient's X-ray.”

“The forensic anthropologist identified the lambda to help determine the age and structural integrity of the skeletal remains.”

Technical

Real-World Examples

“A regularization rate (lambda) controls the strength of regularization, with higher values leading to simpler models and lower values increasing the risk of overfitting.”
Google for Developers · 28 Sept 2026
“Einstein responded by adding a "cosmological constant" to his equations, represented by the Greek letter Lambda.”
ScienceDaily · 18 Aug 2026

Etymology

From Ancient Greek λάμβδα (lámbda). Doublet of lamed.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

Domains

AnatomyFinanceMathematicsPhysicsProgramming

This entry

Level
C2 · Proficiency
Frequency
Occasional
Updated

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