Lambda /ˈlæmdə/[1] (uppercase Λ, lowercase λ; Greek: λάμ(β)δα lám(b)da) is the 11th letter of the Greek alphabet, representing the sound /l/. In the system of Greek numerals lambda has a value of 30. Lambda is derived from the Phoenician Lamed Lamedh. Lambda gave rise to the Latin L and the Cyrillic El (Л). The ancient grammarians and dramatists give evidence to the pronunciation as [laːbdaː] (λάβδα) in Classical Greek times.[2] In Modern Greek the name of the letter, Λάμδα, is pronounced [ˈlam.ða].

In early Greek alphabets, the shape and orientation of lambda varied.[3] Most variants consisted of two straight strokes, one longer than the other, connected at their ends. The angle might be in the upper-left, lower-left ("Western" alphabets), or top ("Eastern" alphabets). Other variants had a vertical line with a horizontal or sloped stroke running to the right. With the general adoption of the Ionic alphabet, Greek settled on an angle at the top; the Romans put the angle at the lower-left.

The HTML 4 character entity references for the Greek capital and small letter lambda are Λ and λ respectively.[4] The Unicode code points for lambda are U+039B and U+03BB.

The Greek alphabet on a black figure vessel, with a Phoenician-lamed-shaped lambda. The gamma has the shape of modern lambda.


Upper-case letter Λ


  1. ^ "lambda". Oxford English Dictionary (3rd ed.). Oxford University Press. September 2005. (Subscription or UK public library membership required.)
  2. ^ Herbert Weir Smyth. A Greek Grammar for Colleges. I.1.c
  3. ^ "Epigraphic Sources for Early Greek Writing". Poinikastas.CSAD.ox.ac.uk. Retrieved 2011-10-03.
  4. ^ "HTML 4.01 Specification. 24. Character entity references in HTML 4". World Wide Web Consortium.
  5. ^ Nelkon, Michael (1977). Fundamentals of Physics. St. Albans, Hertfordshire: Hart-Davis Educational. p. 329.
  6. ^ "Encyclopedia Astronautica: Lambda". Astronautix.com. Archived from the original on 2012-10-22. Retrieved 2012-12-18.
  7. ^ Wankat Separation Process Engineering 2nd ed, Prentice Hall
  8. ^ "Half-Life on Steam". store.steampowered.com. Valve. Retrieved 2017-01-02.