retardation

The act or process of delaying or impeding.

The condition of being delayed or impeded.

The extent to which something is held back or delayed.

Something that retards; a delay or hindrance.

Impaired intellectual development.

A diminishing of tempo; a retard.

The act of retarding or making slower, or its effect; the hindering of motion, growth, or progress, or the hindrance effected; the act of delaying or impeding.

In physics:

A continuous decrement of velocity; a negative acceleration.