retard

American Heritage® Dictionary of the English Language, Fourth Edition

1. v. To cause to move or proceed slowly; delay or impede.
2. v. To be delayed.
3. n. A slowing down or hindering of progress; a delay.
4. n. Music A slackening of tempo.
5. n. Offensive Slang Used as a disparaging term for a mentally retarded person.
6. n. Offensive Slang A person considered to be foolish or socially inept.

Century Dictionary and Cyclopedia

1. To make slow or slower; obstruct in motion or progress; delay; impede; clog; hinder.
2. To defer; postpone; put off.
3. Synonyms To detain, delay.
4. To be delayed or later than usual.
5. n. Retardation.

Wiktionary

1. n. Retardation; delay.
2. n. slang, offensive A person with mental retardation.
3. n. slang, offensive A stupid person, or one who is slow to learn.
4. v. transitive To keep delaying; to continue to hinder; to prevent from progress; to render more slow in progress; to impede; to hinder
5. v. transitive To put off; to postpone.
6. v. transitive, obsolete To be slow or dilatory to perform (something).
7. v. intransitive To decelerate; to slow down.
8. v. intransitive, obsolete To stay back.

GNU Webster's 1913

1. v. To keep delaying; to continue to hinder; to prevent from progress; to render more slow in progress; to impede; to hinder; ; -- opposed to accelerate.
2. v. To put off; to postpone
3. v. obsolete To stay back.
4. n. Retardation; delay.
5. n. Colloq. and disparaging A mentally retarded person.
6. n. Colloq. and disparaging a person who is stupid or inept, especially in social situations.

WordNet 3.0

1. v. lose velocity; move more slowly
2. n. a person of subnormal intelligence
3. v. cause to move more slowly or operate at a slower rate
4. v. be delayed
5. v. slow the growth or development of