retardation

Etymology

retard +‎ -ation

Noun

retardation (countable and uncountable, plural retardations)

1. The act of retarding or delaying; hindrance.
2. The extent to which anything is retarded; the result of any retarding or delay; mental, social, or physical slowness.
3. That which retards; an obstacle; an obstruction.
4. (physics) Deceleration; reduction in the magnitude of velocity.
5. (music) A suspension which resolves upwards.

References

• retardation in The Century Dictionary, The Century Co., New York, 1911
• retardation in Webster’s Revised Unabridged Dictionary, G. & C. Merriam, 1913