1. A classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O
   - ABO blood group system, ABO system

Type of: classification system

• pic
• pica
• pica em
• Pica pica hudsonia
• pica-pica
• picador
• picaninny
• Picardie
• Picardy
• picaresque
• Picariae
• picaro
• picaroon
• Picasso
• picayune
• piccalilli
• piccaninny
• piccolo
• pice
• Picea
• Picea abies
• Picea breweriana
• Picea engelmannii
• Picea glauca
• Picea mariana