[M2.2, P1.3]
generally is: an axis of a graph showing values of a variable [M2.2, P1.3]
as a term, is often used: to describe the third axis of any three-dimensional graph, irrespective of the quantity actually being plotted on that axis. [M2.2, P1.3]
is also: one axis of a Cartesian coordinate system.
Copyright 1997, The Open University