Wiktionary
n. fifteen minutes.
Usage examples of "quarter of an hour".
I occupied myself with the picture for perhaps a quarter of an hour, during which Wilde smoked reflectively, but uttered not one word.
Armed men and women flocked out of the Quarter so fast, and drew even these last dregs after them with such a force of suction, that within a quarter of an hour there was not a human creature in Saint Antoine's bosom but a few old crones and the wailing children.
She then ordered a chicken to be broiled that instant, declaring, if it was not ready in a quarter of an hour, she would not stay for it.
Sure enough, on opening the door of the cabin, they found Sarah Purfoy lying where she had fallen a quarter of an hour before.
It is sufficient that it lasted a full quarter of an hour, at the conclusion of which they retired into the thickest part of the grove.
To this exposition he was obliged to attend near a quarter of an hour, though with great violence to his natural impetuosity, before he was suffered to speak.