micro-

A decimal submultiplier prefix in SI, signifying one millionth of the unit to which it is attached. Symbol, “µ”, but several others have been used. In lists of vitamin pill contents, “microgram” is often abbreviated “mcg”. In copy produced on a typewriter, µ was often represented by the letter “u.” Prefixed to farad, it was often abbreviated as “m,” as in “mmf,” for micromicrofarad.

In Chinese, the micro- is wei.