Webster's Revised Unabridged Dictionary · 1913

Septillion

Septillion , noun

[French septilion, formed from Latin septem seven, in imitation of million.]

According to the French method of numeration (which is followed also in the United States), the number expressed by a unit with twenty-four ciphers annexed. According to the English method, the number expressed by a unit with forty-two ciphers annexed. See Numeration.