The Greek verb huperperisseuo means to overflow beyond all measure, to superabound exceedingly. It is a triple-intensified word: huper (beyond/over) + peri (around/very) + perisseuo (to abound/overflow). Paul may have coined this word to express something for which ordinary language was insufficient.
Huperperisseuo appears in Romans 5:20: 'Where sin increased, grace abounded all the more (huperperisseusen).' This is one of the most breathtaking statements in all of Paul's letters. Sin's escalation does not outrun grace; grace runs faster and higher. The word demands a superlative that normal vocabulary cannot supply — hence the stacking of three intensifiers. This is the logic of the gospel: God's grace is not proportional to human sin; it is categorically beyond it. The verse has sometimes been misread as encouraging sin (Romans 6:1 — 'Shall we go on sinning so that grace may increase?'), which Paul vigorously rejects. Rather, it is a declaration of divine magnanimity: no sin is too great, no failure too deep, for grace to exceed. Huperperisseuo is the vocabulary of superabundant mercy.