retardation

1. The distance by which one wave is behind another. (countable, uncountable)
2. The act of diminishing the rate of speed. (countable, uncountable)
3. A decrease in the speed of telegraph signalling. (countable, uncountable)
4. The extent to which anything is retarded; the result of any retarding or delay; mental, social, or physical slowness. (countable, uncountable)
5. Extreme stupidity. (colloquial, countable, uncountable)
6. That which retards; an obstacle; an obstruction. (countable, uncountable)
7. Deceleration; reduction in the magnitude of velocity. (countable, uncountable)
8. A suspension which resolves upwards. (countable, uncountable)

الجمع retardations