Wage rates that are not readily changed in the face of changes in market conditions. This frequently takes the form of either nominal wage resistance (an unwillingness to accept lower money wages), or real wage resistance (an unwillingness to accept real wage cuts, that is, wage increases less than the rate of inflation). Employers are also unwilling to increase wages in the face of temporary labour shortages, because of anticipated difficulty in lowering them again; and trade unions have been known to oppose their members accepting wage increases not negotiated through them.