- Noun. (physics) a torus-shaped reactor used in the mid-20th Century to carry out experiments in plasma physics and temperature controlled thermonuclear reactions.
- Proper noun. A medieval state roughly equivalent to modern Montenegro.
- Noun. The name of the sixth letter of the modern Greek alphabet ((term, Ζ) , (term, ζ) ) preceded by epsilon ((term, Ε) , (term, ε) ) and followed by eta, ((term, Η) , (term, η) ); or the seventh letter in the ancient Greek alphabet, in which it is preceded by digamma ((term, Ϝ) , (term, ϝ) ).
- Noun. (mathematics) A mathematical function formally known as the Riemann zeta function.