ODD (in middle English odde, from old Norwegian oddi, an angle of a triangle; the old Norwegian oddamann is used of the third man who gives a casting vote in a dispute), that which remains over after an equal division, the unit in excess of an even number; thus in numeration the word is used of a number either above or below a round number, an indefinite cardinal number, as " eighty and odd," or " eighty odd." As applied to individuals, the sense of " one left after a division " leads to that of " solitary," and thus of " uncommon " or " strange." In the plural, " odds " was originally used to denote inequalities especially in the phrase " to make odds even." The sense of a difference in benefit leads to such colloquialisms as " makes no odds," while that of variance appears in the expression " to be at odds." In betting " the odds " is the advantage given by one person to another in proportion to the supposed chances of success.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)