Wordnet 3.0
NOUN (2)
1.
the number that is represented as a one followed by 24 zeros;
- Example: "in England they call a septillion a quadrillion"2.
the number that is represented as a one followed by 15 zeros;
The Collaborative International Dictionary of English v.0.48:
Quadrillion \Quad*ril"lion\, n. [F., fr. L. quater four times,
akin to quattuor four, E. four; -- formed like million. See
Four, Million.]
According to the French notation, which is followed also upon
the Continent and in the United States, a unit with fifteen
ciphers annexed; according to the English notation, the
number produced by involving a million to the fourth power,
or the number represented by a unit with twenty-four ciphers
annexed. See the Note under Numeration.
[1913 Webster] Quadrilobate
WordNet (r) 3.0 (2006):
quadrillion
n 1: the number that is represented as a one followed by 24
zeros; "in England they call a septillion a quadrillion"
2: the number that is represented as a one followed by 15 zeros
Moby Thesaurus II by Grady Ward, 1.0:
29 Moby Thesaurus words for "quadrillion":
a billion, a crore, a lakh, a million, a myriad, a nonillion,
a quadrillion, a thousand, a zillion, decillion, duodecillion,
googol, googolplex, jillion, nonillion, novemdecillion, octillion,
octodecillion, quattuordecillion, quindecillion, quintillion,
septillion, sexdecillion, sextillion, tredecillion, trillion,
undecillion, vigintillion, zillion