micromicrogram

mi·cro·mi·cro·gram (μμg),

(mī'krō-mī'krō-gram), See usage note at micro.Former term for picogram.

micromicrogram

(mī″krō-mī′krō-grăm),

μμg

Obsolete term for 1 millionth of a microgram; now called a picogram, or 10−12gram.