1. Retarded in intellectual development
   - backward, half-witted, feebleminded

See also: retarded, slow-wittedness

• arcsin
• arcsine
• arctan
• arctangent
• arctic
• Arctic Archipelago
• Arctic char
• Arctic Circle
• Arctic fox
• Arctic ground squirrel
• Arctic hare
• arctic moss
• Arctic mouse-ear
• Arctic Ocean
• arctic poppy
• arctic skua
• arctic willow
• Arctic wolf
• Arctic Zone
• Arctictis
• Arctictis bintourong
• arctiid
• arctiid moth
• Arctiidae
• Arctium