pico-
pref.1. One trillionth (10-12): picosecond.
2. Very small: picornavirus.
[Spanish pico, beak, small quantity, from Latin beccus, beak, of Celtic origin (influenced by Spanish picar, to prick).]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
pico-
prefix denoting 10–12: picofarad. Symbol: p
[from Spanish pico small quantity, odd number, peak]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
pico-
a combining form meaning “one trillionth” (10−12): picogram.
[< Sp pico peak, beak, bit]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
pico-
A prefix meaning one trillionth (10-12). For example, 1 picometer = 1 trillionth of a meter.
Dictionary of Unfamiliar Words by Diagram Group Copyright © 2008 by Diagram Visual Information Limited