everydaydefinition meanseffort be excerted.scientific definitionrequires that force act on object and object moves in that direction. example of when is force applied but noworkdone. a roofer carries a bundle of shingles across the roof.

Work in physics is defined as some variation of F * d, where F is the force applied to an object and d is the distance that force moves it. (This definition doesn't always make sense in all situations, like expansion of gasses and such, but the alternate definitions say basically the same thing.)

Now imagine pushing against a wall for a couple of minutes. Your body will certainly feel like you've done some work--your muscles might start to hurt, you might get tired, and so on. But according to F * d, you haven't done any work since the wall didn't actually move when you tried to push it.

Here's another: d is actually just the object's final distance from its original position, so if you pick up a heavy book, throw it in the air a couple times, and put it back exactly where you found it, the amount of work you will have done is zero even though you spent some energy doing it.

Those are the two standard examples. I should mention that biologists define work differently than physicists--they don't ignore the processes happening in your muscles while you do these things, so it's not like you're actually getting free energy or making energy disappear. They're just questions of definition.