DIA
n. countable A1 Beginner US //ˈdiə// dia
n. a single period of twenty-four hours. You use this to talk about time, dates, or the light part of the 24-hour cycle.
n. a period of twenty-four hours as a unit of time, or the interval of light between sunrise and sunset.
Usage
Commonly used in the phrase 'every day' (two words) as an adverbial phrase of frequency.
Pitfall
I go to the gym everyday.I go to the gym every day.'Everyday' is an adjective meaning ordinary; 'every day' is the adverbial phrase meaning each day.