Adverb : sound asleep.    From Dictionary.com. 

Adjective : a sound heart; a sound mind. ,a sound business; sound investments. ,sound judgment. ,sound advice. ,sound moral values. ,sound reasoning. ,sound sleep. ,a sound thrashing. ,a sound title to property.    From Dictionary.com. 

World Economic Forum, Canada has the "soundest" banking system in the world.    From Wordnik.com.  [Trader's Narrative] Reference

Hotel I enjoyed the soundest sleep since leaving home.    From Wordnik.com.  [A Tramp Through the Bret Harte Country] Reference

That racket was enough to awaken the soundest sleeper.    From Wordnik.com.  [Fred Fenton on the Crew or, The Young Oarsmen of Riverport School] Reference

His soundest sleep is always obtained in the diligence.    From Wordnik.com.  [Blackwood's Edinburgh Magazine - Volume 55, No. 343, May 1844] Reference

It is allowed by the soundest philosophers that ridicule has.    From Wordnik.com.  [The Mirror of Taste, and Dramatic Censor, Vol. I, No. 4, April 1810] Reference

I will give you the soundest thrashing you ever had in your life!.    From Wordnik.com.  [Punch, or the London Charivari, Volume 101, August 29, 1891] Reference

From this flooring each selected the soundest stick he could find.    From Wordnik.com.  [Jack Haydon's Quest] Reference

Plot, style, and truthfulness are of the soundest British character.    From Wordnik.com.  [Publisher's Advertising (1872)] Reference

"But as I told you, he is the soundest sleeper I ever traveled with.".    From Wordnik.com.  [Wild Bill's Last Trail] Reference

But his jests were the vehicles for telling to them the soundest truths.    From Wordnik.com.  [Museum of Antiquity A Description of Ancient Life] Reference

All our soundest maxims of political economy are discarded and disgraced.    From Wordnik.com.  [Blackwood's Edinburgh Magazine, Volume 56, Number 349, November, 1844] Reference

They're innocent enough -- really, they're the soundest of sound little nuts.    From Wordnik.com.  [The Shield of Silence] Reference

The wisest and soundest method of solving our tax problem is through economy.    From Wordnik.com.  [US Presidential Inaugural Addresses] Reference

No remedy is known, but we advise the purchase of the soundest and best bulbs.    From Wordnik.com.  [The Culture of Vegetables and Flowers From Seeds and Roots 16th Edition] Reference

The reports have been eagerly read and highly prized by the soundest educators.    From Wordnik.com.  [The New England Magazine, Volume 1, No. 5, Bay State Monthly, Volume 4, No. 5, May, 1886] Reference

Often these time-honored combinations rest upon the soundest of dietetic principles.    From Wordnik.com.  [Vocational Guidance for Girls] Reference

Paglia's soundest point is to suggest that Gaga is closer in spirit to Bette Midler.    From Wordnik.com.  [Tom Gliatto: Lady Gaga and Camille Paglia] Reference

And that will inevitably lead to an extension upon the soundest possible basis of the.    From Wordnik.com.  [Martin Luther King, Jr. Day, 1995, Memorial Issue] Reference

In this work we have some of the soundest and most valuable suggestions we have read.    From Wordnik.com.  [Cattle and Cattle-breeders] Reference

That night the boy was wakened out of his soundest sleep by screams for help in his room.    From Wordnik.com.  [The Book of Stories for the Story-teller] Reference

But the storm of criticism and condemnation which burst upon the platform from the soundest.    From Wordnik.com.  [The Life, Public Services and Select Speeches of Rutherford B. Hayes] Reference

'This is a very admirable and seasonable book, displaying much reading and the soundest views.    From Wordnik.com.  [The Hero of the Humber or the History of the Late Mr. John Ellerthorpe] Reference

The operations of Nature exhibit the soundest philosophy, and the most perfect examples of art.    From Wordnik.com.  [A Practical Enquiry into the Philosophy of Education] Reference

These the final words before the townsman-bandit had himself dropped off into soundest slumbers.    From Wordnik.com.  [Bakemono Yashiki (The Haunted House), Retold from the Japanese Originals Tales of the Tokugawa, Volume 2] Reference

Charles Lamb and Talfourd praise him as not only the most brilliant, but the soundest of critics.    From Wordnik.com.  [The Atlantic Monthly, Volume 06, No. 35, September, 1860] Reference

Opinions such as these are based on the soundest common sense, indeed no one could honestly oppose them.    From Wordnik.com.  [The Art of Living in Australia ; together with three hundred Australian cookery recipes and accessory kitchen information by Mrs. H. Wicken] Reference

Puritans were right who said, that the soundest conversions were those with which the law had most to do.    From Wordnik.com.  [The Wesleyan Methodist Pulpit in Malvern Sermons Preached at the Opening Services of the Wesleyan Methodist Chapel, in 1866] Reference

From one of the soundest pilots of the Royal Naval Air Service I heard his experience of the previous day.    From Wordnik.com.  [Some Naval Yarns] Reference

As for the nobleman himself, he declared that he was the happiest and soundest of all the Czar's subjects.    From Wordnik.com.  [Doctor Jones' Picnic] Reference

The American people have always recognized that education is one of the soundest investments they can make.    From Wordnik.com.  [State of the Union Address (1790-2001)] Reference

I was even then very much impressed with Mr. Hanna as a man of the very soundest judgment and common sense.    From Wordnik.com.  [Fifty Years of Public Service] Reference

That the project has the interest of our soundest statesmen and scholars may be seen from the fact that the President of the.    From Wordnik.com.  [The New England Magazine Volume 1, No. 6, June, 1886, Bay State Monthly Volume 4, No. 6, June, 1886] Reference

'Pinnacled dim in the intense inane' -- no contact can be wholesomer than the contact with Burns at his archest and soundest.    From Wordnik.com.  [Harvard Classics Volume 28 Essays English and American] Reference

In October 2008, in fact, the World Economic Forum proclaimed Canada to have the soundest banking system on the entire planet.    From Wordnik.com.  [Canada Grows Up] Reference

His moral and religious principles are not only unexceptionable, but they are founded on the soundest and most enlightened basis.    From Wordnik.com.  [Blackwood's Edinburgh Magazine, Volume 61, No. 379, May, 1847] Reference

The expense attendant upon such a modification of the executive department would be justified by the soundest principles of economy.    From Wordnik.com.  [State of the Union Address (1790-2001)] Reference

So he replaced his ankle band, locked the catch, and lay down to the soundest and most refreshing sleep he had enjoyed for many a night.    From Wordnik.com.  [In Clive's Command A Story of the Fight for India] Reference