a short time; a brief moment
A yojijukugo meaning a very short period of time, often used in literary or formal contexts. Literally 'one day, a fragment of time'.
I cannot waste even a single moment.
寸暇 also means a brief moment, but is more common and less literary than 一日片時.
一刻 means a moment or a short while, but is more neutral in register and more widely used.
A yojijukugo composed of 一日 (one day) and 片時 (a short time, a moment). The combination emphasizes the brevity of time.