KEY: Retard.
SYN: Clog, hinder, obstruct, impede, defer.
ANT: Accelerate, expedite, promote.
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KEY: Retentive.
SYN: Preservative, close, tenacious, mindful.
ANT: Loose, leaky, oblivious.
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KEY: Reticence.
SYN: Reserve, silentness, refrain, repressiveness.