— trillionth , n. , adj.
/tril"yeuhn/ , n. , pl. trillions , ( as after a numeral ) trillion , adj.
n.
1. a cardinal number represented in the U.S. by 1 followed by 12 zeros, and in Great Britain by 1 followed by 18 zeros.
adj.
2. amounting to one trillion in number.
[ 1680-90; tr ( i )- TRI- + ( m ) illion MILLION ]