Definition of zetas:
(n) :
The sixth letter of the modern Greek alphabet (Ζ, ζ) preceded by epsilon (Ε, ε) and followed by eta, (Η, η); or the seventh letter in the ancient Greek alphabet, in which it is preceded by digamma (Ϝ, ϝ)
(n) :
(mathematics) A mathematical function, formally known as the Riemann zeta function.
(n) :
A member of Los Zetas, a Mexican criminal syndicate.
(n) :
(historical) medieval state roughly equivalent to modern Montenegro.
(n) :
(physics) Acronym of zero-energy thermonuclear assembly/apparatus (“a torus-shaped reactor used in the mid-20th century to carry out experiments in plasma physics and temperature-controlled thermonuclear reactions”).