Ordinal v Cardinal

The other day I was chatting with a hummingbird. Said hummingbird asked, "What's the difference between 'ordinal' and 'cardinal'?"

I was tempted to reply in the manner of my immediate male ancestor, "The former comes mostly in black, the latter comes mostly in red — like in roulette, you know. The zero is both black and red and hence is neither ordinal nor cardinal, or could be both."

Fortunately for the hummingbird, I chose to give a less spurious and more serious reply.

'Ordinal' comes from Latin ordo, a sequence or progression (hence, 'order'). 'Cardinal' comes from Latin cardo, a hinge (and hence, a critical point). Ordinals are therefore things which depend on sequence and do not stand on their own, while cardinals are things that stand on their own.

For example, 'first', 'second', and 'third' are ordinals which are linked to the cardinals 'one', 'two' and 'three' respectively. If you think of 'one', 'two' and 'three' as 'counting numbers', then they are being thought of in an ordinal sense, since they are being thought of as part of a counting sequence. But if you think of them as 'integers', then they are being thought of in a cardinal sense, since an integer is literally 'intact', 'whole' or 'untouched' (with a secondary sense of 'standing upright and alone').

Here is where we find the idea of 'extraordinary' — something which is beyond or outside the normal order or sequence of things. Related to the same root is 'coordination' — having sequences of events that are related to each other.

But beware of false etymologies: 'cardinal' has nothing to do with 'cardiological', despite the common association with the colour red. The latter comes from the Greek kardia, which means 'heart'.