The words oliguria, polyuria and nycturia are used in this paper to indicate different types of abnormality in urine volume, although in most dictionaries they have a double meaning and may designate changes either in the frequency of urination or in the amount of urine.
At present these words can be used only in a general descriptive sense, and are only applicable with any certainty in those instances in which the deviation from the volumes ordinarily observed is extreme. This is so not on account of any lack of measurements of the volume of urine in normal persons but because these measurements have been made under such varying conditions that the range of normal variation is wide and its limits uncertain. A definition of oliguria, polyuria and nycturia which would give the terms a quantitative significance requires a statistical determination of the distribution of the urine volumes of normal subjects
ADDIS T. THE CLINICAL SIGNIFICANCE OF ABNORMALITIES IN URINE VOLUMES. Arch Intern Med (Chic). 1923;31(6):783-796. doi:10.1001/archinte.1923.00110180002001