The time of noon; the time of day when the sun is highest in the sky, especially on a hot day. / (figuratively) The time of greatest prosperity.

plural of noonday

A demon, thought to be active at the noon hour, that inclines its victims (usually monastics) to restlessness, excitability and inattention to their duties. Used as a synonym for acedia (Greek ακηδία (akidía)).

plural of noonday devil