overwork >> əʊvəˈwəːk
Definition: [verb] cause (someone) to work beyond their capacity or strength.
Example: employers should be aware that overworking their employees comes at a cost
Definition: [verb] make excessive use of.
Example: we aren't building new refineries so we have overworked our old ones
Definition: [noun] excessive work.
Example: his health broke down under the strain of overwork