• WordNet 3.6
    • adj challenging requiring full use of your abilities or resources "ambitious schedule","performed the most challenging task without a mistake"
    • adj challenging disturbingly provocative "an intriguing smile"
    • adj challenging stimulating interest or thought "a challenging hypothesis","a thought-provoking book"
    • ***


  • Yoshihisa Tabuchi
    Yoshihisa Tabuchi
    “It's always the challenge of the future, this feeling of excitement, that drives me.”
  • Travis White
    Travis White
    “Dreams can often become challenging, but challenges are what we live for.”
  • Source Unknown
    Source Unknown
    “You can't expect to meet the challenges of today with yesterday's tools and expect to be in business tomorrow.”
  • Lou Holtz
    “How you respond to the challenge in the second half will determine what you become after the game, whether you are a winner or a loser.”
  • Muhammad Ali
    “It's lack of faith that makes people afraid of meeting challenges, and I believe in myself.”
  • Henry Wadsworth Longfellow
    “Critics are sentinels in the grand army of letters, stationed at the corners of newspapers and reviews, to challenge every new author.”


In literature:

Thus did Captain Pond accept our challenge.
"The Mayor of Troy" by Sir Arthur Thomas Quiller-Couch
So I hurried Daggett up; made him keep on sending challenge after challenge.
"Chapters from My Autobiography" by Mark Twain
Flood and Mr. Fair had arranged for a ride in the flume, and I was challenged to go with them.
"Hidden Treasures" by Harry A. Lewis
She turned to me again, holding out her hand as though she challenged me to refuse it.
"Simon Dale" by Anthony Hope
She held her head a bit high, as if in challenge.
"The Triflers" by Frederick Orin Bartlett
Ojeda finally challenged Nicuesa to a duel which should determine the whole affair.
"South American Fights and Fighters" by Cyrus Townsend Brady
For all that, I must clear the bar, if I was to make good my challenge; and I drew a long breath as I stood a moment and glanced round.
"Sir Ludar" by Talbot Baines Reed
His supremacy as a printer could not be challenged in Bursley.
"Clayhanger" by Arnold Bennett
Still, he could not be angry when, on being challenged, the girl laughed at him.
"The Magnificent Montez" by Horace Wyndham
We would be challenged, then brought down.
"Tarrano the Conqueror" by Raymond King Cummings

In poetry:

O the bliss upon the plains,
Where the joining heroes clashed
Shield and spear, and, unabashed,
Challenged with hot chariot-reins
Gods!—they glimmer ocean-washed.
"Cassandra" by George Meredith
'Farewell timeless expanse of passing years!
Farewell, woman who flung your challenge steeled
Against the abyss of humiliations:
For it is I who am your battlefield!
"August" by Boris Pasternak
No sound of tramping hoofs, no yelling pack,
No merry winding of the hunter's horn,
Rous'd sleeping echo to fling boldly back
The challenge rude, as if in mocking scorn.
"Elegy" by Janet Hamilton
The sounds that met my boyish ear
My inward sense salute,--
The woodnotes wild I loved to hear,--
The robin's challenge, sharp and clear,--
The breath of evening's flute.
"Our Home—Our Country" by Oliver Wendell Holmes
The yellow kitten purred on the hearth,
While the kitchen clock, with its frame of oak,
In the corner stood, like a sentinel,
And challenged time with its measured stroke.
"Phoebe's Wooing" by Horatio Alger Jr
One moment, as if challenging the storm,
Chocorua's tall, defiant sentinel
Looked from his watch-tower; then the shadow fell,
And the wild rain-drift blotted out his form.
"Storm On Lake Asquam" by John Greenleaf Whittier

In news:

Keeping them is the challenge.
In sharp turnaround, nation challenges Saudi Arabian production.
The Aragon weekend was particularly challenging for the Ducati Team and its riders, who are working to speed up the development of the Desmosedici.
TOLEDO, Ohio – The pursuit of the Hoosier Tire Superspeedway Challenge Award will feature eight races in 2013, up from seven in 2012, following yesterday's announcement of an ARCA Racing Series event at Kentucky Speedway.
The Nixon Surf Challenge heads to the Lofoten Islands in Norway.
To actually start drilling, Shell needs federal certification of the Arctic Challenger, shown above.
Eli is facing arguably the most challenging year of his career, yet he remains confident.
On Your Marks is a monthly column where reporter John Marks takes on competition from the greater Lake Wylie and Fort Mill areas, challenging them in their field of expertise and profiling what makes them special.
Strikeforce women's bantamweight championship Ronda Rousey applies an arm bar to challenger Sarah Kaufman during their bout Saturday at Valley View Casino Center.
China's newest stealth fighter prototype is made in the People's Republic and could pose a challenge to US air power.
CHINA is challenging India as a low-cost home for software development.
Arnold Palmer 's younger grandson gets call for Father/Son Challenge.
During the fourth week of their million dollar challenge the community puts on a high-end wine and dine event, but with expensive ticket prices and an inexperienced staff, will anyone show up and will they be satisfied with the event.
Okay, I know this doesn't look for reals, but Lord Monckton, a former policy adviser to Margaret Thatcher, has challenged Al Gore to a Climate Change Challenge (for the fancy cursive you'll have to click on the link).
Navigating today's roads can be challenging for all drivers, but military veterans face particular challenges behind the wheel.

In science:

While in the initial stages of a system, this challenge has been echoed as the ‘cold-start’ problem (also referred to as the ‘day-one’ or ‘early-rater’ problem), it is also ubiquitous during the lifetime of a system.
A Connection-Centric Survey of Recommender Systems Research
The lack of standards to represent such information and its sources (e.g., logs) in a uniform manner make interoperability among recommender systems a challenge [19, 30].
A Connection-Centric Survey of Recommender Systems Research
Furthermore, connecting users wi th similar interests who have rated different items (e.g., ‘we both read world politics online, but he ranked webpages, while I ranked pages’) is challenging.
A Connection-Centric Survey of Recommender Systems Research
The need for an optimized model is motivated by the ma jor challenges faced in a basic OAI-PMH model, which can be seen in Figure 1.
A Scalable Architecture for Harvest-Based Digital Libraries - The ODU/Southampton Experiments
However, the proof of such a statement does present some challenges.
A law of large numbers for random walks in random mixing environments