Question

Define zero work in details

Answer 1

No work is said to be done by a force if the force is acting at right angles to the displacement of the body 
                                   OR
If the force does not produce any displacement.
Example:- The work done by the force of gravity on a box lying on the roof of a bus moving with constant velocity on a straight road.
When a man pushes a wall, no displacement is caused and here it is zero work done

Answer 2

According to science work is defined as product of force and displacement where displacement is in the direction of force w = F x S
Work will be zero when there is no displacement even there is application of force
Eg - if you lift a bag standing in a place then you have applied your muscular force to lift the bag but your displacement is 0 as u didn't move from that place (displacement is zero) then work done by you is zero