NonAB

NonAB is a term used in various domains to indicate something that is not AB. It does not have a single standardized definition across disciplines, and its meaning is often inferred from context. In many references, nonAB serves as a general shorthand for categories or items that lie outside the AB designation.

In ABO blood group contexts, nonAB typically refers to any blood type other than AB, namely A, B, and O. Individuals with nonAB types carry antibodies against the A or B antigens corresponding to their own phenotype. This distinction has practical implications for transfusion medicine: AB plasma, which contains no anti-A or anti-B antibodies, is considered the universal plasma donor, while plasma from nonAB types carries antibodies that can react with recipient ABO antigens and thus requires careful matching. For red blood cell transfusions, ABO compatibility remains essential, and nonAB designations help organize donor–recipient matching in databases and protocols.

In data labeling and research, nonAB is often used as a label to denote items outside the AB class. For example, in datasets where AB represents a specific category or condition, nonAB marks all other cases. This usage is informal and highly dependent on the study design or project conventions, underscoring the importance of defining terms within each context.

Because nonAB lacks a universal definition, users encountering the term should reference the specific field, dataset, or document to determine how nonAB is defined in that setting. See also AB, ABO blood groups, and plasma transfusion.