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1. A decrease in rate of change
   "the retardation of the arms race";
   - deceleration, slowing
    
2. The extent to which something is delayed or held back
    
3. Any agent that retards, delays or hinders
   "flame-retardation";
   - retardant, retardent, retarder
    
4. Lack of normal development of intellectual capacities
   - mental retardation, backwardness, slowness, subnormality
    
5. The act of slowing down or falling behind
   - slowdown, lag

Derived forms: retardations

Type of: agent, alteration, change, daftness [informal], delay, hold, holdup, modification, postponement, stupidity, time lag, wait

Encyclopedia: Retardation