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

• melanism
• melanite
• Melanitta
• Melanitta nigra
• melanize
• melanoblast
• melanocyte
• melanocyte-stimulating hormone
• melanoderma
• Melanogrammus
• Melanogrammus aeglefinus
• melanoma
• Melanoplus
• melanosis
• melanotic
• Melanotis
• Melanotis caerulescens
• Melanthiaceae
• melasma
• Melastoma
• Melastoma malabathricum
• Melastomaceae
• Melastomataceae
• melatonin
• Melba