from The American Heritage® Dictionary of the English Language, 4th Edition
- n. One trillionth (10-12) of a second.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. An SI unit of time equal to 10−12 seconds.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. one trillionth (10^-12) of a second; one thousandth of a nanosecond
From the metric prefix pico- and the word second (Wiktionary)