Mysteries of vernacular:

Odd,

different from what is usual or expected.

Though the modern word odd has many meanings,

mathematical or not,

they can all be traced back

to the Indo-European root uzdho,

meaning pointing upwards.

Inspired by the idea

of a vertical-pointed object,

speakers of Old Norse modified this root

into a new word, oddi,

which was used to refer to a triangle,

the simplest pointed object

geometrically speaking.

A triangle with a long point,

like an arrow head

or a piece of land jutting out into the sea,

was recognized to have two paired angles

and a third that stood alone.

And over time, oddi began to refer

to something that wasn't matched or paired.

In Old Norse, oddi also came to mean

any number indivisible by two.

And odda mathr, the odd man,

was used to describe the unpaired man

whose vote could break a tie.

Though the English never called a triangle odd,

they did borrow the odd number

and the odd man.

And finally, in the 16th century,

the notion of the odd man out

gave rise to our modern meaning peculiar.