Lord knows

Lord knows

1. No one knows (except for God). Lord knows how long it will take for my application to be processed. A: "How do you think you did on your exam?" B: "Lord knows!"
2. It is absolutely true, certain, or definite that; it is obvious or clear that. Lord knows I need to do well on this test or I can kiss my scholarship goodbye!
See also: know, lord

Lord knows (that) I've tried

It is the absolute truth that I have tried my best (to do something). A: "You and Jeff just need to spend some time together and bond." B: "Lord knows I've tried. That boy just isn't interested in doing anything other than playing those damned video games." A: "You need to convince her to accept the deal." B: "Lord knows that I've tried, but she is adamantly refusing." A: "Then try harder!"
See also: know, lord, tried
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

ˈLord (ˈonly) knows (what, where, why, etc.)...

(spoken) used to say that you do not know the answer to something: She comes and goes as she pleases. Lord knows when we’ll see her again.‘Why did she say that?’ ‘Lord knows!’(Some people may find this use offensive.)
See also: lord
Farlex Partner Idioms Dictionary © Farlex 2017

Lord (only) knows, the

Who knows? I certainly don’t. The locution that only God knows the answer to something dates from the eighteenth century or earlier. (It is also put as God knows and Heaven knows.) Defoe wrote (The True-Born Englishman, 1701), “Great families of yesterday we show, and lords, whose parents were the Lord knows who,” and a few decades later Swift wrote (Polite Conversation, 1738), “Lord of the Lord knows what.”
See also: lord
The Dictionary of Clichés by Christine Ammer Copyright © 2013 by Christine Ammer
See also:
References in classic literature ?
I seem to be wandering off in search of Lord knows what, Lord knows where.
"Lord bless you, Missis!" said Sam, "horses won't be cotched all in a mimit; they'd done clared out way down to the south pasture, and the Lord knows whar!"
"Sam, how often must I tell you not to say `Lord bless you, and the Lord knows,' and such things?
There is something that almost nips your breath in the idea that a dozen men, descended from the Lord knows whom, stopped a war which would have altered the whole face of history."
We've got enough to endure at the hands of the men, the Lord knows, so I hold we hadn't ought to clapper-claw one another, and it isn't often you'll find me running down another woman.
And, says he, "We have found only this partridge, but the Lord knows what mischief they have done."
And something did, for the next summer was made memorable by the prevalence of a mysterious disease--epidemic, endemic, or the Lord knows what, though the physicians didn't--which carried away a full half of the population.
"Here, Robin, change your raiment with me, and we will see if my lord knows an old woman when he sees her."
We've been found to be the greatest gentlefolk in the whole county--reaching all back long before Oliver Grumble's time--to the days of the Pagan Turks--with monuments, and vaults, and crests, and "scutcheons, and the Lord knows what all.
(Lord knows how!) into talking about foreign parts; I mean the place she lived in before they sent her to England.
'My dear fellow--and you must permit me to say again, that you never looked so young; so positively boyish as you do to-night--the Lord knows where; I believe Columbus himself wouldn't find them.
Pullet continued, shaking her head and looking at her sister Tulliver, "when you and me chose the double diamont, the first flax iver we'd spun, and the Lord knows where yours is gone."
Your aunt would put it off till the Lord knows when, but he is anxious to be bound as soon as may be: he won't hear of waiting beyond next month; and you, I guess, will be of the same mind, so - '
it's a matter o' some moment to me, that ye've chairged wi' stealin' the letter, and making a market o't, and Lord knows what besides, that I suld hae yer ain acknowledgment for it in black and white.
The Lord knows she's nothing to look at and you scarcely ever hear her speak, but she did what none of us dare do.