Hey, A-to-Z-ers! You still hanging in there?
Odd first showed up in the early fourteenth century, but only as a word for an uneven number. Because an uneven number is unpaired and thus, “left out”, odd grew to mean peculiar, because obviously there’s something wrong with it if it’s unpaired. Anyway, odd comes from the Old Norse oddi, which figuratively means something like third or a tie-breaker (as in a vote), but literally means an angle or point of land (apparently, the notion of a triangle morphed it into that third definition, which is, shall we say, an odd transformation). Oddi comes from the Proto Germanic word uzdaz, pointed upward, and further back, the Proto Indo European uzdho-.
University of Texas at Austin Linguistic Research Center