retard

from The Century Dictionary.

• noun Retardation.
• To make slow or slower; obstruct in motion or progress; delay; impede; clog; hinder.
• To defer; postpone; put off.
• Synonyms To detain, delay.
• To be delayed or later than usual.

from the GNU version of the Collaborative International Dictionary of English.

• intransitive verb obsolete To stay back.
• transitive verb To keep delaying; to continue to hinder; to prevent from progress; to render more slow in progress; to impede; to hinder; ; -- opposed to accelerate.
• transitive verb To put off; to postpone
• noun Retardation; delay.
• noun Colloq. and disparaging A mentally retarded person.
• noun Colloq. and disparaging a person who is stupid or inept, especially in social situations.
• noun the interval between the transit of the moon at which a tide originates and the appearance of the tide itself. It is found, in general, that any particular tide is not principally due to the moon's transit immediately proceeding, but to a transit which has occured some time before, and which is said to correspond to it. The retard of the tide is thus distinguished from the lunitidal interval. See under Retardation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Retardation; delay.
• noun slang, offensive A person with mental retardation.
• noun slang, offensive A stupid person, or one who is slow to learn.
• verb transitive To keep delaying; to continue to hinder; to prevent from progress; to render more slow in progress; to impede; to hinder
• verb transitive To put off; to postpone.
• verb transitive, obsolete To be slow or dilatory to perform (something).
• verb intransitive To decelerate; to slow down.
• verb intransitive, obsolete To stay back.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb lose velocity; move more slowly
• noun a person of subnormal intelligence
• verb cause to move more slowly or operate at a slower rate
• verb be delayed
• verb slow the growth or development of