lambda

Concise Oxford English Dictionary © 2008 Oxford University Press:
lambda /ˈlamdə/

▶noun

• 1 the eleventh letter of the Greek alphabet (Λ, λ), transliterated as ‘l’.

• 2 Anatomy the point at the back of the skull where the parietal bones and the occipital bone meet.

▶symbol (λ)

• 1 wavelength.

• 2 Astronomy celestial longitude.

– origin from Gk.