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

• facilitatory
• facility
• facing
• facing pages
• facsimile
• facsimile machine
• fact
• fact mood
• fact of life
• fact-finding
• facticity
• faction
• factional
• factionalism
• factious
• factiously
• factitious
• factitive
• factoid
• factor
• factor analyse
• factor analysis
• factor analytic
• factor analytical
• factor analyze