Lambda/ˈlæmdə/ Definition 1 of 5Pro Tip 1/2Greek Origin Understand that 'lambda' originates from Greek culture and refers to its alphabet. Learning Greek letters like alpha, beta, and lambda can be fun! Pro Tip 2/2Pronunciation Key Pronounce 'lambda' as 'LAM-duh', with emphasis on the first syllable. The symbol for 50 in Greek numerals is 'lambda'.