To retard something is to slow it down. A lack of fresh fruit and vegetables can retard the growth of a young child.

This word should be used with a lot of caution. Calling someone who's mentally retarded — or of low intelligence — a retard is considered very offensive by many people. That use should be avoided. On the other hand, this is a harmless word when used as a verb. While skiing, a heavy, bulky jacket could retard your progress down the mountain. Keeping a plant out of sunlight would retard its growth. When you see retard, think slow and "Use with caution."

Definitions of retard

v cause to move more slowly or operate at a slower rate

“This drug will retard your heart rate”
lessen the momentum or velocity of
Type of:
decelerate, slow down
reduce the speed of

v lose velocity; move more slowly

decelerate, slow, slow down, slow up
accelerate, quicken, speed, speed up
move faster
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slow, slow down, slow up
cause to proceed more slowly
delay, detain, hold up
cause to be slowed down or delayed
bog, bog down
cause to slow down or get stuck
clog, constipate
impede with a clog or as if with a clog
engage in delaying tactics or refuse to cooperate
delay or hold up; prevent from proceeding on schedule or as planned
deliberately delay an event or action
buy time
act so as to delay an event or action in order to gain an advantage
Type of:
decrease, diminish, fall, lessen
decrease in size, extent, or range

v slow the growth or development of

“The brain damage will retard the child's language development”
check, delay
check; keep in check (a fire)
delay, detain, stay
stop or halt
Type of:
alter, change, modify
cause to change; make different; cause a transformation

v be delayed

Type of:
have the quality of being; (copula, used with an adjective or a predicate noun)

n a person of subnormal intelligence

changeling, cretin, half-wit, idiot, imbecile, moron
a person suffering from Down syndrome (no longer used technically in this sense)
Type of:
simple, simpleton
a person lacking intelligence or common sense

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