Q: Your posting on the idiomatic use of prepositions with “odd” and “even” left me to wondering how these two little words got their numerical meanings.
A: And now we’ve been wondering about the conventions of “odd” and “even” numbering.
Let’s begin with “even” and save the odder history of “odd” for later.
The adjective “even” has had several related meanings over its more than 1,000-year history.
Among other things, it has meant level, equal, alike, uniform, straight, direct, parallel, exact, precise, balanced, and equable (that is, unruffled).
In the mid-16th century, the Oxford English Dictionay says, “even” acquired a numerical meaning: “divisible integrally into two equal parts.”
“Even” first appeared this way, according to OED citations, in Robert Record’s The Whetstone of Witte (1557): “Euen nombers are those, whiche maie be diuided into equalle halfes.”
It’s easy to see how a word that meant equal could evolve over a few hundred years into one that meant dividable into equal parts.
The adjective “odd,” however, didn’t have to evolve to get its numerical sense.
It’s been used for numbers since it showed up in a Middle English religious poem in the late 13th century, according to OED references.
The original meaning of “odd” in English was one in addition to (or one shy of) an even number.
“Odd” got this meaning from associations it had in early Scandinavian.
For example, oddi in Old Icelandic meant a triangle, and later a third or an odd number. Here’s how the OED explains it:
“The senses ‘odd,’ ‘odd number’ in early Scandinavian apparently developed by metaphor from ‘triangle’ (as being three-cornered), and thence by extension from the third or unpaired member of a group of three, to any single or unpaired member of a group, and from three as the primary ‘odd number,’ to all numbers containing an unpaired unit.”
Meanwhile, a century of so after it entered English, “odd” started taking on non-numerical meanings: left over, unpaired, irregular, strange, and generally the opposite of “even.”
So “even” developed its numerical meaning because of an earlier sense of evenness, while “odd” developed its sense of oddness because of an earlier numerical meaning.
Now isn’t that odd!
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