Micro-

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Micro (Greek letter μ, mu, non-italic) is a unit prefix in the metric system denoting a factor of 10⁻⁶ (one millionth).^[1] It comes from the Greek word μικρός (mikrós), meaning "small".^[2]

It is the only SI prefix which uses a character not from the Latin alphabet. In Unicode, the symbol is represented by U+03BC μ GREEK SMALL LETTER MU or the legacy symbol U+00B5 µ MICRO SIGN. The prefix "mc" is commonly used in healthcare or when the character "μ" is not available; for example, "mcg" commonly denotes a microgram.^[3] The letter "u" is sometimes used instead of "μ" when non-Latin characters are not available.