hundred-millionth adjective 1noun 1forms 1 adjective1 •The ordinal form of the number one hundred million. noun1 •One of one hundred million equal parts of a whole.Old weighing instruments couldn’t even measure a mite (1/8750 ounce), much less a blanc, which would have been about a hundred-millionth of an ounce. — 1996 formshundred-millionths
