Λ

Symbol

 * 1)  the cosmological constant
 * 2)  the von Mangoldt function
 * 3)  the de Bruijn-Newman constant
 * 4)  a lambda particle
 * 5)  the empty string

Etymology
From.

Letter

 * 1) The letter lambda, the 11th letter of the ancient Greek alphabet.

Letter

 * 1) The upper case letter lambda (λάμδα), the eleventh letter of the modern Greek alphabet.

Numeral

 * 1) The number thirty in Greek numerals.

,Λ
 * 1) The number 30,000 in Greek numerals.