(logic) A formula in the language of an axiomatic system, in which one or more schematic variables appear, which stand for any term or subformula of the system, which may or may not be required to satisfy certain conditions.

A set of axioms or axiom schemata from which theorems can be derived.

(anatomy) Any plane that divides the body into superior and inferior parts, roughly perpendicular to spine.

Vitamin A

(mathematics) The following axiom (applied to an ordered field): for any subset of the given ordered field, if there is any upper bound for this subset, then there is also a supremum for this subset, and this supremum is an element of the given ordered field (though not necessarily of the subset).

A trailer having only a single axle or group of axles, positioned at or near the centre of gravity.

(mathematics) Any point that lies on any of the axes of a coordinate system / (optics) nodal point

Without an axe.

(UK dialectal) plural of ash

(set theory) One of the axioms in axiomatic set theory, equivalent to the statement that two sets are equal if and only if they contain the same elements.