Kuzushi it basically means balance. Kuzushi is such an important concept in Jiu Jitsu that it’s interesting we don’t talk about it more. I recall when I first learned about it, I thought it was just a translation. It seems more than that though. All throws in Jiu Jitsu require it in some way. Your kuzushi doesn’t have to be off by much, just an inch or two will do it. Don’t believe me? Stand up and move your head back an inch or two. Notice the weight shifting to your heels?
One might say “You won’t be able to throw him until you’ve broken his kuzushi.”
George Kirby described it “The concept, called kuzushi, holds that once continuity is broken, your technique — whatever it may be — has a greater chance of succeeding.” in Japanese-jujitsu-for-self-defense-much-more-than-just-joint-locks.
JudoInfo.com has a nice article about kuzushi too.
Check out the crazy images people have used in describing and defining the concept here.