The brain and the spinal cord

(set theory) The axiom that the power set of any set exists and is a valid set, which appears in the standard axiomatisation of set theory, ZFC.

(set theory) A weaker form of the axiom of choice that states that every countable collection of nonempty sets must have a choice function; equivalently, the statement that the direct product of a countable collection of nonempty sets is nonempty.

(rail transport) A safety device fitted to railway track which counts the axles in a train as it passes over it. A check is carried out when the train passes the next axle counter to make sure the train is still complete.

plural of axle counter

plural of axiom schema

plural of axle loading

(transport, rail transport) the weight placed on each axle of a vehicle.

(mineralogy) A tetragonal mineral containing arsenic, chlorine, copper, fluorine, sodium and oxygen

(set theory) One of the axioms in axiomatic set theory, equivalent to the statement that if two sets exist, there exists a set with those two sets as its sole elements.