1. Disease of infancy and early childhood characterized by pain and swelling in, and pink coloration of, the fingers and toes.
2. A syndrome caused almost exclusively by mercury poisoning in children and gastrointestinal symptoms, in adults, by anorexia, photophobia, sweating, and tachycardia (fast heart beat).
3. Etymology: from Greek acro, "extreme, top" + Greek odyne, "pain"; literally a ain in an extremity; such as, the hands or the feet.