Λ

Lambda (; uppercase ', lowercase ; , ; , ), sometimes rendered lamda, labda or lamma', is the eleventh letter of the Greek alphabet, representing the voiced alveolar lateral approximant ; it derives from the Phoenician letter Lamed, and gave rise to Latin L and Cyrillic El (). In the system of Greek numerals, lambda has a value of 30. The ancient grammarians typically called it (, ) in Classical Greek times, whereas in Modern Greek it is (, ), while the spelling () was used (to varying degrees) throughout the lengthy transition between the two.

In early Greek alphabets, the shape and orientation of lambda varied. 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.