— septillionth , n. , adj.
/sep til"yeuhn/ , n. , pl. septillions , ( as after a numeral ) septillion , adj.
n.
1. a cardinal number represented in the U.S. by 1 followed by 24 zeros, and in Great Britain by 1 followed by 42 zeros.
adj.
2. amounting to one septillion in number.
[ 1680-90; sept SEVEN + -illion, as in MILLION ]