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

• Kyrgyzstani monetary unit
• Kyrie
• Kyrie eleison
• Kyushu
• Kyyiv
• Kyzyl Kum
• KZN
• Köln
• l
• L'Aquila
• L'Enfant
• L-dopa
• L-P
• L-plate
• L-shaped
• L. M. Montgomery
• L. monocytogenes
• L. Ron Hubbard
• L. S. Lowry
• la
• La Fontaine
• La Paz
• La Plata
• La Rochefoucauld
• La Spezia