prothrombin prothrift • prothrombin accelerator · · · Info · Definitions · Synonyms · Characters · · prothrombin · · Text Latin · · Script 11 · · Length 3 · · Syllables Definitions · · · (noun) a protein in blood plasma that is the inactive precursor of thrombin. Synonyms: factor II. · · Noun Definition 1 Synonyms · · · factor ii · · Synonym 1 Characters · · b latin small letter b U+0062 h latin small letter h U+0068 i latin small letter i U+0069 m latin small letter m U+006D n latin small letter n U+006E o latin small letter o U+006F p latin small letter p U+0070 r latin small letter r U+0072 t latin small letter t U+0074