Meaning

noun a very large indefinite number (usually hyperbole)

noun the number that is represented as a one followed by 18 zeros

noun the number that is represented as a one followed by 12 zeros

originBorrowed from French trillion, from French tri- (“three”) + -illion, equivalent to tri- + -illion. The noun was coined by American basketball player Harvey Pollack, because of the way the numbers read across a basketball box score.

Etymology from Wiktionary, CC BY-SA 3.0