Wiktionary
phr. (label en idiomatic intensifier) unceasingly; very; thoroughly; to a very high degree.
Usage examples of "as the day is long".
Dishonest as the day is long, but clever as sin and twice as dangerous.
And you shall do nothing but what you choose, and shall be as happy as the day is long, and shall keep Cousin Clifford in spirits with the wisdom and pleasantness which is always dropping from your lips!
She was good-natured enough, but as dull-witted as the day is long.
He was twenty-eight years old and, though a bit dull-witted, honest as the day is long, honorable and not in the least craven.
Schnitzius was the room's scapegoat, good-natured as the day is long, but so hopelessly undertalented that he was the self-appointed victim of every one of his superiors from the Stabsfeldwebel down.
Schnitzius was the room's scapegoat, good-natured as the day is long, but so hopelessly undertalented that he was the self-appointed victim of every one of his superiors from the stabsfeldwebel down.
He's single, knows ranching like the back of his hand, and is as dependable as the day is long.
Advantage of wealth and power makes this available to them, but it's ersatz as the day is long.