abo system abortus • abouchement · · · Info · Definitions · Characters · · abo system · · Text Common · · Latin · · Scripts 10 · · Length 4 · · Syllables Definitions · · · (noun) a classification system for the antigens of human blood; used in blood transfusion therapy; four groups are A and B and AB and O. Synonyms: ABO blood group system, ABO system, ABO group. · · Noun Definition 1 Characters · · space U+0020 a latin small letter a U+0061 b latin small letter b U+0062 e latin small letter e U+0065 m latin small letter m U+006D o latin small letter o U+006F s latin small letter s U+0073 t latin small letter t U+0074 y latin small letter y U+0079