Have you seen the movies where "cardinals" are members of the Sacred College, ranking next after the pope, who elect the pope and act as his chief counsellors or something like that? They are always "important people". The term cardinal some from Latin "cardinālis", literally: relating to a hinge, hence, that on which something depends, principal, from cardō hinge. When you hear or read "cardinal" just think about something important and basic. I hope you understand :)

I know that in Astrology, four signs are "cardinal". The Cardinal signs are those during which monthly period, the Summer and Winter Solstices occur, and the Spring and Fall Equinoxes occur. (Solstice & Equinox are different terms for the same thing, which is the sun passing over a certain point in its seasonal travels) "The four cardinal signs are: Aries (Aries.svg), the Sun's passage through which begins the spring in the northern hemisphere, and the autumn in the southern hemisphere. Cancer (Cancer.svg), which begins the summer in the northern hemisphere, and the winter in the southern hemisphere. Libra (Libra.svg), which begins the autumn in the northern hemisphere, and the spring in the southern hemisphere. Capricorn (Capricorn.svg), which begins the winter in the northern hemisphere, and the summer in the southern hemisphere."----Wikipedia The resource you need to conduct your research is called an ETYMOLOGICAL DICTIONARY. Here is a weblink to one that continually appears: http://www.etymonline.com http://www.etymonline.com/index.php?term=cardinal