setback

An unanticipated or sudden check in progress; a change from better to worse.

A steplike recession in a wall.

Any of a series of such recessions in the rise of a tall building.

An automatically timed setting of a thermostat to a lower temperature, as in the home at night.

Any game in which a failure to score is counted by setting back the player instead of allowing his adversary to add the points to his score: usually restricted to games such as all-fours, in which there is bidding for the trump.