from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A unit of mass equal to one thousandth (10-3) of a milligram or one millionth (10-6) of a gram.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A unit of mass equal to 0.000 001 grams. Symbol: μg or mcg
from The Century Dictionary and Cyclopedia
- n. The millionth part of a gram, being about of a grain troy.
- n. A photograph or a drawing of a microscopic object.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. one millionth (1/1,000,000) gram
It takes 1000 grams to make a kilogram, so that means a microgram is a billionth of a kilogram.
Each dose contains 50 micrograms (a microgram is one-millionth of a gram and a gram is the weight of one-fifth of a teaspoon of water).
A microgram is a millionth of a gram; a deciliter is one-tenth of a liter.
Section VI of the proposal covers the challenges and risks to laser weapons ... mainly that of cheaply producing large quantities of Polonium-210 (currently produced only in microgram quantities, and extremely lethal).
In the years 1986 to 1991, the average adult in the United States consumed an average of 0.8 micrograms (a microgram is a millionth of a gram) of DDT a day.
Now, the point about polonium is of course that we need, as you just said, very tiny amounts, a microgram, which is a millionth of gram, of polonium will do terrible damage to you once inside your body.
In the most recent studies, lead was not detectable in most foods and the average dietary intake of lead was about 1 microgram (a microgram is a millionth of a gram) per kilogram of body weight/day.
Since some xenobiotics are toxic in much smaller quantities than the milligram, smaller fractions of the gram are used, such as microgram (µg).
The Federal Safe Drinking Water Act standards have a drinking water criteria for total mercury at 2 ppb or 2 microgram per liter (ug/L).
This was true even at high exposure where the average toenail mercury levels were 1 microgram per gram — roughly twice the recommended limit for pregnant women.