Micro-

Look up micro- in Wiktionary, the free dictionary.

Micro (Greek letter μ, mu, non-italic) is a unit prefix in the metric system denoting a factor of one millionth (10^-6).^[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.

When Latin characters are not available, the letter "u" is sometimes used instead of "μ". The prefix "mc" is also commonly used; for example, "mcg" denotes a microgram.^[3]