What is the meaning of Setback?

An obstacle, delay, disadvantage, or blow (an adverse event which slows down, or prevents progress towards a desired outcome).

Any adverse event, defeat, or impediment of progress.

The required distance between a structure and a road.

A step-like recession in a wall.

An offset to the temperature setting of a thermostat to cover a period when more or less heating is required than usual.

A backset; a countercurrent; an eddy.

A backset; a check; a repulse; a relapse.

Source: wiktionary.org