Five; the fifth in a series.
From Latin quintus, fifth.
If their Latin origins were the only factor, quinti‑ would mean ‘fifth’ and quinque‑ would mean ‘five’, but this distinction has long been lost. A quintet contains five members, a quintile is any one of five equal groups into which a population can be divided, a quintuplet is one of five children born to the same mother at one birth, and to quintuple something is to increase it fivefold. For quintillion, see the entry Number words.