de Bruijn-Newman constant

Etymology
Named after the mathematicians Nicolaas Govert de Bruijn and Charles M. Newman.

Proper noun

 * 1)  A mathematical constant, denoted by Λ, defined via the zeros of a certain function H(λ, z), where λ is a real parameter and z is a complex variable. H has only real zeros if and only if λ ≥ Λ. The Riemann hypothesis is equivalent to the conjecture that Λ ≤ 0.