A plant whose leaves are used as spinach-like greens, Tetragonia tetragonioides

(grammar) The absence of an ending after a noun‐stem in a language in which endings are normally applied; often written as ∅

(mathematics) The fact that, in some circumstances, the probability of an event can only be zero or one and not any intermediate value.

The mass of water in a lake or ocean not close to the bottom and not near the shore.

(education) A high school class that is offered early in the morning, before the scheduled start of the school day.

A species of falcon endemic to New Zealand, Falco novaeseelandiae.

(embryology) A region of mesenchymal connective tissue that carries instructions which direct the developing limb bud to form along the anterior-posterior axis.

(historical) A former area between Saudi Arabia and Iraq, abolished 1991.

(mathematics) A type of potential counterexample to the generalized Riemann hypothesis, on the zeros of Dirichlet L-function.

An area with no life. / (ecology) An area of the ocean where oxygen levels are too low to support life, especially as a result of pollution.