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