Cardinal means of the very first importance. A cardinal rule, a cardinal error, of cardinal importance.
The Latin cardo means a hinge, so a cardinal thing is one everything else turns on — and that image runs through every use. Cardinal numbers are one, two, three, as against ordinal first, second, third. A cardinal in the church, and the red bird, take the name from the same importance.
1adjectivecardinalOf the very first importance.
“The cardinal rule of the kitchen is to wash your hands before touching food.”
cardinal is a quality of importance.
The Latin behind it names the point a door turns on. The cardinal rules are the ones everything else turns on.
hooks ontoturn
Latin cardinalis means of a hinge, from cardo, a hinge. A cardinal point is one the rest turns on.
Latin
cardinālis
Middle French
cardinal
English, today
cardinal
Built from
Borrowed from Middle French cardinal, from Latin cardinālis. From Middle French cardinal, from Latin cardinālis (“pertaining to a hinge, hence applied to that on which something turns or depends, important, principal, chief”), from cardin-, cardō (“hinge”) + -ālis, adjectival suffix.
Etymology from Wiktionary, CC BY-SA