Of fundamental importance (formed as cardinal1).
cardinal humour each of the four chief humours of the body.
cardinal number a number denoting quantity (one, two, three, etc.) as opposed to an ordinal number (first, second, third, etc.).
cardinal points the four main points of the compass (north, south, east, and west).
cardinal virtues the chief moral attributes of scholastic philosophy: justice, prudence, temperance, and fortitude, identified by the classical philosophers and adopted by Christian moral theologians.