all-out definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
complete or wholehearted: an all-out effort
all-out definition by American Heritage Dictionary
With every possible effort: worked all out to make the deadline.
The American Heritage® Dictionary of the English Language, 4th edition Copyright © 2010 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Using all available means or resources: an all-out sprint; an all-out conservation program.
all-out - Phrases/Idioms
With all one's strength, ability, or resources; not holding back. For example, They are going all out to make the fund-raiser a success. This seemingly modern term dates from about 1300, when it meant “completely” or “wholly.” It now refers to making a great effort and is also used adjectivally, as in an all-out effort. This usage became current in America in the late 1800s, with reference to races and other kinds of athletic exertion. In the mid-1900s it gave rise to the phrase to go all out and was transferred to just about any energetic undertaking. Also see go whole hog.