micr(o)-word element [Gr.], small; also used in naming units of measurement (symbol μ) to designate an amount one millionth (10−6) the size of the unit to which it is joined, e.g., microgram.
word element. [Gr.] small; used in naming units of measurement to designate an amount 10−6 (one-millionth) the size of the unit to which it is joined; symbol μ, e.g. microgram (μg).