noun
(mathematics, dated) An integer that is less than another, but that does not divide the other integer into integral parts.
(chemistry) A portion of a total amount (of some substance or a sample/specimen thereof) that does not divide evenly into it, thus leaving a (nonzero) remainder.
(chemistry, loosely, sometimes proscribed) Synonym of aliquot.
adjective
(mathematics, dated) Less than another specified integer, but not dividing it into integral parts.