A full cycle of day and night: twenty-four hours taken as a single unit, with darkness acknowledged as half the measure. A nychthemeron insists on wholeness, light and dark as one completed turn.

From Greek nychthēmeron, from nyx/nych- "night" + hēmera "day." A stitched seam of time: night and day yoked into one term, as they are in lived experience.